通过dfs求排列

#include <stdio.h>
#include "stdlib.h"
int book[10],a[10],n,t;
int comp(const void*a,const void*b)
{
    return *(int*)b-*(int*)a;
}
void dfs(int num,int time,int m)
{
    int i;
    if(m==time)
    {
        for(i=1;i<=m;i++)
            printf("%d ",a[i]);
        printf("\n");
        return;
    }
    for(i=1;i<=num;i++)
        if(book[i]==0)
        {
            m++;
            a[m]=i;
            book[i]=1;
            dfs(num,time,m);
            book[i]=0;
            m--;
        }
    return;
}
int main(int argc, const char * argv[])
{
    scanf("%d %d",&n,&t);
    dfs(n,t,0);
    return 0;
}