全排列

#include<stdio.h>
void premutation(int pos,int n);
char c[100];
char used[200];
char pre[100];
int main()
{
    int n;
    scanf("%d",&n);
    getchar();
    gets(c);
    premutation(0,n);
    return 0;
}

void premutation(int pos,int n)
{
    if(pos == n)
        {
            for(int i=0;i<n;i++)
                 printf("%c ",pre[i]);
            printf("\n");
            return ;
        }
    for(int i=0;i<n;i++)
        {
            if(used[i]==0)
                {
                    pre[pos]=c[i];
                    used[i]=1;
                    premutation(pos+1,n);
                    used[i]=0;
                }
        }
    return ;
}
#include<stdio.h>   //全排列去重
#include<string.h>
void premutation(int pos,int n);
char c[100];
int used[200];
char pre[100];
int main()
{
    int n;
    scanf("%d",&n);
    getchar();
    gets(c);
    for(int i=0;i<strlen(c);++i)
     used[c[i]]++;  //统计相同字符的个数
    premutation(0,n);
    return 0;
}
void premutation(int pos,int n)
{
    if(pos == n)
        {
            for(int i=0;i<=n;i++)
                 printf("%c ",pre[i]);  //输出全排列后的
            printf("\n");
            return ;
        }
    for(int i=65;i<=122;i++)
        {
            if(used[i]>0)
                {
                    pre[pos]=i;
                    used[i]--; 
                    premutation(pos+1,n);
                    used[i]++;
                }
        }
    return ;
}