全排列（递归与非递归）

递归算法

inline void Swap(char& a, char& b) 
{// 交换a和b 
    char temp = a; 
    a = b; 
    b = temp; 
} 

void Perm(char list[], int k, int m) 
{ //生成list [k：m ]的所有排列方式 
    int i; 
    if (k == m) {//输出一个排列方式 
        for (i = 0; i <= m; i++) 
            putchar(list[i]); 
        putchar('\n'); 
    } 
    else // list[k：m ]有多个排列方式 
        // 递归地产生这些排列方式 
        for (i=k; i <= m; i++) { 
            Swap (list[k], list[i]); 
            Perm (list, k+1, m); 
            Swap (list [k], list [i]); 
        } 
} 

 

/* By Nathan from if-else.org, Jun 29 */
#include<stdio.h>
#include<string.h>
#define pop(str) strcpy(str, stack[--top])
#define push(str) strcpy(stack[top++], str)
#define N 5
inline static char* insert( char* str, int i );  /* insert a new char to the str at position i */
static char str[N+1], stack[N*(N-1)/2][N+1], tmp_str[N+1];
static int len, top;
int main ()
{
        push("1");            /* push the root */
        while( top > 0 ) {      /* exit after all leaves have been visited */
                pop(str);
                if( (len = strlen(str)) >= N )
                        printf( "%s\n", str ); /* current node has reached the leaf */
                else
                        for( int i = 0; i <= len; i++ ) /* keep pushing brothers */
                                push( insert( str, i ) );
        }
        return 0;
}
inline static char* insert( char* str, int i )
{
        strcpy(tmp_str,str);
        for( int j = len; j >= i; j--)
                *(tmp_str + j + 1) = *(tmp_str + j);
        *(tmp_str+i) = len + '1'; /* len+'1' happens to indicate the number to insert*/
        return tmp_str;
}

非递归算法