编写一个程序来反转数组或字符串-yiteyi-C++库

给定一个数组（或字符串），任务是反转数组/字符串。 例如：

null

Input  : arr[] = {1, 2, 3}Output : arr[] = {3, 2, 1}Input :  arr[] = {4, 5, 1, 2}Output : arr[] = {2, 1, 5, 4}

建议：请在“上解决” 实践 “首先，在讨论解决方案之前。

迭代方式：

1）将开始和结束索引初始化为开始=0，结束=n-1 2）在循环中，将arr[start]与arr[end]交换，并按如下方式更改start和end：开始=开始+1，结束=结束–1

reverse-a-number

另一个反转字符串的示例：

reverse-a-string

以下是上述方法的实施情况：

C++

                         // Iterative C++ program to reverse an array                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         /* Function to reverse arr[] from start to end*/                       
                         void                                     rvereseArray(                                     int                                     arr[],                                     int                                     start,                                     int                                     end)                       
                         {                       
                                                 while                                     (start < end)                       
                                                 {                       
                                                 int                                     temp = arr[start];                       
                                                 arr[start] = arr[end];                       
                                                 arr[end] = temp;                       
                                                 start++;                       
                                                 end--;                       
                                                 }                       
                         }                       
           
                         /* Utility function to print an array */                       
                         void                                     printArray(                                     int                                     arr[],                                     int                                     size)                       
                         {                       
                                                 for                                     (                                     int                                     i = 0; i < size; i++)                       
                                                 cout << arr[i] <<                                     " "                                     ;                       
           
                                                 cout << endl;                       
                         }                       
           
                         /* Driver function to test above functions */                       
                         int                                     main()                       
                         {                       
                                                 int                                     arr[] = {1, 2, 3, 4, 5, 6};                       
                                   
                                                 int                                     n =                                     sizeof                                     (arr) /                                     sizeof                                     (arr[0]);                       
           
                                                 // To print original array                       
                                                 printArray(arr, n);                       
                                   
                                                 // Function calling                       
                                                 rvereseArray(arr, 0, n-1);                       
                                   
                                                 cout <<                                     "Reversed array is"                                     << endl;                       
                                   
                                                 // To print the Reversed array                       
                                                 printArray(arr, n);                       
                                   
                                                 return                                     0;                       
                         }                       

C

                         // Iterative C program to reverse an array                       
                         #include<stdio.h>                       
           
                         /* Function to reverse arr[] from start to end*/                       
                         void                                     rvereseArray(                                     int                                     arr[],                                     int                                     start,                                     int                                     end)                       
                         {                       
                                                 int                                     temp;                       
                                                 while                                     (start < end)                       
                                                 {                       
                                                 temp = arr[start];                       
                                                 arr[start] = arr[end];                       
                                                 arr[end] = temp;                       
                                                 start++;                       
                                                 end--;                       
                                                 }                       
                         }                       
           
                         /* Utility that prints out an array on a line */                       
                         void                                     printArray(                                     int                                     arr[],                                     int                                     size)                       
                         {                       
                                                 int                                     i;                       
                                                 for                                     (i=0; i < size; i++)                       
                                                 printf                                     (                                     "%d "                                     , arr[i]);                       
           
                                                 printf                                     (                                     ""                                     );                       
                         }                       
           
                         /* Driver function to test above functions */                       
                         int                                     main()                       
                         {                       
                                                 int                                     arr[] = {1, 2, 3, 4, 5, 6};                       
                                                 int                                     n =                                     sizeof                                     (arr) /                                     sizeof                                     (arr[0]);                       
                                                 printArray(arr, n);                       
                                                 rvereseArray(arr, 0, n-1);                       
                                                 printf                                     (                                     "Reversed array is "                                     );                       
                                                 printArray(arr, n);                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Iterative java program to reverse an                       
                         // array                       
                         public                                     class                                     GFG {                       
                                   
                                                 /* Function to reverse arr[] from                       
                                                 start to end*/                       
                                                 static                                     void                                     rvereseArray(                                     int                                     arr[],                       
                                                 int                                     start,                                     int                                     end)                       
                                                 {                       
                                                 int                                     temp;                       
                                   
                                                 while                                     (start < end)                       
                                                 {                       
                                                 temp = arr[start];                       
                                                 arr[start] = arr[end];                       
                                                 arr[end] = temp;                       
                                                 start++;                       
                                                 end--;                       
                                                 }                       
                                                 }                       
                                   
                                                 /* Utility that prints out an                       
                                                 array on a line */                       
                                                 static                                     void                                     printArray(                                     int                                     arr[],                       
                                                 int                                     size)                       
                                                 {                       
                                                 for                                     (                                     int                                     i =                                     0                                     ; i < size; i++)                       
                                                 System.out.print(arr[i] +                                     " "                                     );                       
                                   
                                                 System.out.println();                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String args[]) {                       
                                   
                                                 int                                     arr[] = {                                     1                                     ,                                     2                                     ,                                     3                                     ,                                     4                                     ,                                     5                                     ,                                     6                                     };                       
                                                 printArray(arr,                                     6                                     );                       
                                                 rvereseArray(arr,                                     0                                     ,                                     5                                     );                       
                                                 System.out.print(                                     "Reversed array is "                                     );                       
                                                 printArray(arr,                                     6                                     );                       
                                   
                                                 }                       
                         }                       
           
                         // This code is contributed by Sam007                       

python

                         # Iterative python program to reverse an array                       
           
                         # Function to reverse A[] from start to end                       
                         def                                     reverseList(A, start, end):                       
                                                 while                                     start < end:                       
                                                 A[start], A[end]                                     =                                     A[end], A[start]                       
                                                 start                                     +                                     =                                     1                       
                                                 end                                     -                                     =                                     1                       
           
                         # Driver function to test above function                       
                         A                                     =                                     [                                     1                                     ,                                     2                                     ,                                     3                                     ,                                     4                                     ,                                     5                                     ,                                     6                                     ]                       
                         print                                     (A)                       
                         reverseList(A,                                     0                                     ,                                     5                                     )                       
                         print                                     (                                     "Reversed list is"                                     )                       
                         print                                     (A)                       
                         # This program is contributed by Pratik Chhajer                       

C#

                         // Iterative C# program to reverse an                       
                         // array                       
                         using                                     System;                       
           
                         class                                     GFG {                       
           
                                                 /* Function to reverse arr[] from                       
                                                 start to end*/                       
                                                 static                                     void                                     rvereseArray(                                     int                                     []arr,                       
                                                 int                                     start,                                     int                                     end)                       
                                                 {                       
                                                 int                                     temp;                       
                                   
                                                 while                                     (start < end)                       
                                                 {                       
                                                 temp = arr[start];                       
                                                 arr[start] = arr[end];                       
                                                 arr[end] = temp;                       
                                                 start++;                       
                                                 end--;                       
                                                 }                       
                                                 }                       
                                   
                                                 /* Utility that prints out an                       
                                                 array on a line */                       
                                                 static                                     void                                     printArray(                                     int                                     []arr,                       
                                                 int                                     size)                       
                                                 {                       
                                                 for                                     (                                     int                                     i = 0; i < size; i++)                       
                                                 Console.Write(arr[i] +                                     " "                                     );                       
                                   
                                                 Console.WriteLine();                       
                                                 }                       
                                   
                                                 // Driver function                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     []arr = {1, 2, 3, 4, 5, 6};                       
                                                 printArray(arr, 6);                       
                                                 rvereseArray(arr, 0, 5);                       
                                                 Console.Write(                                     "Reversed array is "                                     );                       
                                                 printArray(arr, 6);                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Sam007                       

PHP

                         <?php                       
                         // Iterative PHP program                       
                         // to reverse an array                       
           
                         /* Function to reverse                       
                         $arr from start to end*/                       
                         function                                     rvereseArray(&                                     $arr                                     ,                                     $start                                     ,                       
                                                 $end                                     )                       
                         {                       
                                                 while                                     (                                     $start                                     <                                     $end                                     )                       
                                                 {                       
                                                 $temp                                     =                                     $arr                                     [                                     $start                                     ];                       
                                                 $arr                                     [                                     $start                                     ] =                                     $arr                                     [                                     $end                                     ];                       
                                                 $arr                                     [                                     $end                                     ] =                                     $temp                                     ;                       
                                                 $start                                     ++;                       
                                                 $end                                     --;                       
                                                 }                       
                         }                       
           
                         /* Utility function to                       
                                                 print an array */                       
                         function                                     printArray(&                                     $arr                                     ,                                     $size                                     )                       
                         {                       
                         for                                     (                                     $i                                     = 0;                                     $i                                     <                                     $size                                     ;                                     $i                                     ++)                       
                         echo                                     $arr                                     [                                     $i                                     ] .                                     " "                                     ;                       
           
                         echo                                     ""                                     ;                       
                         }                       
           
                         // Driver code                       
                         $arr                                     =                                     array                                     (1, 2, 3, 4, 5, 6);                       
           
                         // To print original array                       
                         printArray(                                     $arr                                     , 6);                       
           
                         // Function calling                       
                         rvereseArray(                                     $arr                                     , 0, 5);                       
           
                         echo                                     "Reversed array is"                                     .                                     ""                                     ;                       
           
                         // To print the Reversed array                       
                         printArray(                                     $arr                                     , 6);                       
           
                         // This code is contributed                       
                         // by ChitraNayal                       
                         ?>                       

输出：

1 2 3 4 5 6 Reversed array is 6 5 4 3 2 1

时间复杂性： O（n） 递归方式：

1）将开始和结束索引初始化为开始=0，结束=n-1 2）将arr[开始]与arr[结束]交换 3）对数组的其余部分递归调用reverse。

以下是上述方法的实施情况：

C++

                         // Recursive C++ program to reverse an array                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         /* Function to reverse arr[] from start to end*/                       
                         void                                     rvereseArray(                                     int                                     arr[],                                     int                                     start,                                     int                                     end)                       
                         {                       
                                                 if                                     (start >= end)                       
                                                 return                                     ;                       
                                   
                                                 int                                     temp = arr[start];                       
                                                 arr[start] = arr[end];                       
                                                 arr[end] = temp;                       
                                   
                                                 // Recursive Function calling                       
                                                 rvereseArray(arr, start + 1, end - 1);                       
                         }                       
           
           
                         /* Utility function to print an array */                       
                         void                                     printArray(                                     int                                     arr[],                                     int                                     size)                       
                         {                       
                                                 for                                     (                                     int                                     i = 0; i < size; i++)                       
                                                 cout << arr[i] <<                                     " "                                     ;                       
           
                                                 cout << endl;                       
                         }                       
           
                         /* Driver function to test above functions */                       
                         int                                     main()                       
                         {                       
                                                 int                                     arr[] = {1, 2, 3, 4, 5, 6};                       
                                   
                                                 // To print original array                       
                                                 printArray(arr, 6);                       
                                   
                                                 // Function calling                       
                                                 rvereseArray(arr, 0, 5);                       
                                   
                                                 cout <<                                     "Reversed array is"                                     << endl;                       
                                   
                                                 // To print the Reversed array                       
                                                 printArray(arr, 6);                       
                                   
                                                 return                                     0;                       
                         }                       

C

                         // Recursive C program to reverse an array                       
                         #include <stdio.h>                       
           
                         /* Function to reverse arr[] from start to end*/                       
                         void                                     rvereseArray(                                     int                                     arr[],                                     int                                     start,                                     int                                     end)                       
                         {                       
                                                 int                                     temp;                       
                                                 if                                     (start >= end)                       
                                                 return                                     ;                       
                                                 temp = arr[start];                       
                                                 arr[start] = arr[end];                       
                                                 arr[end] = temp;                       
                                                 rvereseArray(arr, start+1, end-1);                       
                         }                       
           
                         /* Utility that prints out an array on a line */                       
                         void                                     printArray(                                     int                                     arr[],                                     int                                     size)                       
                         {                       
                                                 int                                     i;                       
                                                 for                                     (i=0; i < size; i++)                       
                                                 printf                                     (                                     "%d "                                     , arr[i]);                       
           
                                                 printf                                     (                                     ""                                     );                       
                         }                       
           
                         /* Driver function to test above functions */                       
                         int                                     main()                       
                         {                       
                                                 int                                     arr[] = {1, 2, 3, 4, 5, 6};                       
                                                 printArray(arr, 6);                       
                                                 rvereseArray(arr, 0, 5);                       
                                                 printf                                     (                                     "Reversed array is "                                     );                       
                                                 printArray(arr, 6);                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Recursive Java Program to reverse an array                       
                         import                                     java.io.*;                       
           
                         class                                     ReverseArray {                       
           
                                                 /* Function to reverse arr[] from start to end*/                       
                                                 static                                     void                                     rvereseArray(                                     int                                     arr[],                                     int                                     start,                                     int                                     end)                       
                                                 {                       
                                                 int                                     temp;                       
                                                 if                                     (start >= end)                       
                                                 return                                     ;                       
                                                 temp = arr[start];                       
                                                 arr[start] = arr[end];                       
                                                 arr[end] = temp;                       
                                                 rvereseArray(arr, start+                                     1                                     , end-                                     1                                     );                       
                                                 }                       
           
                                                 /* Utility that prints out an array on a line */                       
                                                 static                                     void                                     printArray(                                     int                                     arr[],                                     int                                     size)                       
                                                 {                       
                                                 for                                     (                                     int                                     i=                                     0                                     ; i < size; i++)                       
                                                 System.out.print(arr[i] +                                     " "                                     );                       
                                                 System.out.println(                                     ""                                     );                       
                                                 }                       
           
                                                 /*Driver function to check for above functions*/                       
                                                 public                                     static                                     void                                     main (String[] args) {                       
                                                 int                                     arr[] = {                                     1                                     ,                                     2                                     ,                                     3                                     ,                                     4                                     ,                                     5                                     ,                                     6                                     };                       
                                                 printArray(arr,                                     6                                     );                       
                                                 rvereseArray(arr,                                     0                                     ,                                     5                                     );                       
                                                 System.out.println(                                     "Reversed array is "                                     );                       
                                                 printArray(arr,                                     6                                     );                       
                                                 }                       
                         }                       
                         /*This article is contributed by Devesh Agrawal*/                       

python

                         # Recursive python program to reverse an array                       
           
                         # Function to reverse A[] from start to end                       
                         def                                     reverseList(A, start, end):                       
                                                 if                                     start >                                     =                                     end:                       
                                                 return                       
                                                 A[start], A[end]                                     =                                     A[end], A[start]                       
                                                 reverseList(A, start                                     +                                     1                                     , end                                     -                                     1                                     )                       
           
                         # Driver function to test above function                       
                         A                                     =                                     [                                     1                                     ,                                     2                                     ,                                     3                                     ,                                     4                                     ,                                     5                                     ,                                     6                                     ]                       
                         print                                     (A)                       
                         reverseList(A,                                     0                                     ,                                     5                                     )                       
                         print                                     (                                     "Reversed list is"                                     )                       
                         print                                     (A)                       
                         # This program is contributed by Pratik Chhajer                       

C#

                         // C# program to reverse an array                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
                                                 /* Function to reverse arr[]                       
                                                 from start to end*/                       
                                                 static                                     void                                     rvereseArray(                                     int                                     []arr,                                     int                                     start,                       
                                                 int                                     end)                       
                                                 {                       
                                                 int                                     temp;                       
                                                 if                                     (start >= end)                       
                                                 return                                     ;                       
                                   
                                                 temp = arr[start];                       
                                                 arr[start] = arr[end];                       
                                                 arr[end] = temp;                       
                                   
                                                 rvereseArray(arr, start+1, end-1);                       
                                                 }                       
           
                                                 /* Utility that prints out an                       
                                                 array on a line */                       
                                                 static                                     void                                     printArray(                                     int                                     []arr,                                     int                                     size)                       
                                                 {                       
                                                 for                                     (                                     int                                     i =  0; i < size; i++)                       
                                                 Console.Write(arr[i] +                                     " "                                     );                       
                                   
                                                 Console.WriteLine(                                     ""                                     );                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     Main ()                       
                                                 {                       
                                                 int                                     []arr = {1, 2, 3, 4, 5, 6};                       
                                   
                                                 printArray(arr, 6);                       
                                                 rvereseArray(arr, 0, 5);                       
                                   
                                                 Console.WriteLine(                                     "Reversed array is "                                     );                       
                                                 printArray(arr, 6);                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Sam007                       

PHP

                         <?php                       
                         // Iterative PHP program                       
                         // to reverse an array                       
           
                         /* Function to reverse                       
                         $arr from start to end*/                       
                         function                                     rvereseArray(&                                     $arr                                     ,                       
                                                 $start                                     ,                                     $end                                     )                       
                         {                       
                                                 if                                     (                                     $start                                     >=                                     $end                                     )                       
                                                 return                                     ;                       
                                   
                                                 $temp                                     =                                     $arr                                     [                                     $start                                     ];                       
                                                 $arr                                     [                                     $start                                     ] =                                     $arr                                     [                                     $end                                     ];                       
                                                 $arr                                     [                                     $end                                     ] =                                     $temp                                     ;                       
           
                                                 //Recursive Function calling                       
                                                 rvereseArray(                                     $arr                                     ,                                     $start                                     + 1,                       
                                                 $end                                     - 1);                       
                         }                       
           
                         /* Utility function                       
                         to print an array */                       
                         function                                     printArray(&                                     $arr                                     ,                                     $size                                     )                       
                         {                       
                         for                                     (                                     $i                                     = 0;                                     $i                                     <                                     $size                                     ;                                     $i                                     ++)                       
                         echo                                     $arr                                     [                                     $i                                     ] .                                     " "                                     ;                       
           
                         echo                                     ""                                     ;                       
                         }                       
           
                         // Driver code                       
                         $arr                                     =                                     array                                     (1, 2, 3, 4, 5, 6);                       
           
                         // To print original array                       
                         printArray(                                     $arr                                     , 6);                       
           
                         // Function calling                       
                         rvereseArray(                                     $arr                                     , 0, 5);                       
           
                         echo                                     "Reversed array is"                                     .                                     ""                                     ;                       
           
                         // To print the Reversed array                       
                         printArray(                                     $arr                                     , 6);                       
           
                         // This code is contributed                       
                         // by ChitraNayal                       
                         ?>                       

输出：

1 2 3 4 5 6 Reversed array is 6 5 4 3 2 1

时间复杂性： O（n）

另一种方法： 使用Python列表切片

蟒蛇3

                         def                                     reverseList(A):                       
                                                 print                                     ( A[::                                     -                                     1                                     ])                       
                                   
                         # Driver function to test above function                       
                         A                                     =                                     [                                     1                                     ,                                     2                                     ,                                     3                                     ,                                     4                                     ,                                     5                                     ,                                     6                                     ]                       
                         print                                     (A)                       
                         print                                     (                                     "Reversed list is"                                     )                       
                         reverseList(A)                       

输出：

[1, 2, 3, 4, 5, 6]
Reversed list is
[6, 5, 4, 3, 2, 1]

如果您在上述程序或其他解决相同问题的方法中发现任何错误，请写评论。

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