nyoj 32 组合数

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;
int num, limit;
int a[12];
bool visit[12];

void DFS(int x, int cur, int deep) //入口、当前层、总层数
{
	if(cur > deep) //结束条件
		return ;
	for(int i = x; i >= 1; --i)
	{
		if(!visit[i])
		{
			visit[i] = true;
			a[cur] = i;
			if(cur == deep)
			{
				for(int i = 1; i <= deep; ++i)
					printf("%d", a[i]);
				printf("\n");
			}
			DFS(i - 1, cur + 1, deep);
			visit[i] = false;
		}
	}
}

int main()
{

	while(~scanf("%d%d", &num, &limit))
	{
		memset(visit, false, sizeof(visit));
		DFS(num, 1, limit);
	}
	return 0;
}