Write a C program to print all permutations of a given string

最新推荐文章于 2024-06-13 23:50:34 发布

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本文介绍了一种使用回溯法实现的字符串排列算法，并给出了详细的代码示例。该算法能有效地生成给定字符串的所有可能排列。

A permutation, also called an “arrangement number” or “order,” is a rearrangement of the elements of an ordered list S into a one-to-one correspondence with S itself. A string of length n has n! permutation.
Source: Mathword(http://mathworld.wolfram.com/Permutation.html)

Below are the permutations of string ABC.

ABC, ACB, BAC, BCA, CAB, CBA

Here is a solution using backtracking.

# include <stdio.h> 
/* Function to swap values at two pointers */ 
void swap (char *x, char *y) 
{     
    char temp;     
    temp = *x;     
    *x = *y;     
    *y = temp; 
}   
/* Function to print permutations of string    
This function takes three parameters:   
 1. String    2. Starting index of the string    
 3. Ending index of the string. */ 
 void permute(char *a, int i, int n)  
 {    
     int j;     
     if (i == n)      
     printf("%s\n", a);    
     else   
     {         
        for (j = i; j <= n; j++)        
        {           
            swap((a+i), (a+j));           
            permute(a, i+1, n);           
            swap((a+i), (a+j)); 
            //backtrack        
        }    
    } 
}   

/* Driver program to test above functions */ 
int main() 
{    
    char a[] = "ABC"; 
    permute(a, 0, 2);    
    getchar();    
    return 0; 
}

Output: