递归实例——C语言实现全排列

#include "stdafx.h"
void permutation(char s[], int b, int e) //被排列的数组中不能有重复的元素
{
if(0<=b && b<=e)
{
if(b==e)
{
printf("%s\n",s);
}
else
{
int i = 0;
for(i=b; i<=e; i++)
{
char c = s[b];
s[b] = s[i];
s[i] = c;

permutation(s, b+1, e);

c = s[b];
s[b] = s[i];
s[i] = c;
}
}
}
}

void permutation_2(char s[], int b, int e) //被排列的数组中可以有重复的元素
{
static int count = 0;
char repeat[sizeof(s)/sizeof(char)] = {NULL}; //用于存储重复的元素
if(0<=b && b<=e)
{
if(b==e)
{
count++;
printf("%d: %s\n",count,s);
}
else
{
int i = 0;
int j = 0;
int t = 0; //记录重复元素的个数
int repeat_num = 0; //记录连续重复元素的个数
int flag = 0;
for(i=b; i<=e; i++)
{
for(j = 0;j<t;j++)
{
if(s[i]==repeat[j])
{
flag = 1;
repeat_num++;
break;
}
}
if(flag == 1)
{
continue;
}
else
{
repeat[t] = s[i];
t++;
char c = s[b];
s[b] = s[i];
s[i] = c;

permutation_2(s, b+1+repeat_num, e);

c = s[b];
s[b] = s[i];
s[i] = c;
}
}
}
}
}

int _tmain(int argc, _TCHAR* argv[])
{
char s[] = "abbcccc";
permutation_2(s,0,6);
return 0;
}