uva 729

题意：给你一串二进制串，而前N-M是0，后M位是1，让你生成它之后的全排列，next_permutation()解决

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

char s[20];

int main()
{
	int t;
	scanf("%d",&t);
	while (t--)
	{
		int a,b;
		scanf("%d%d",&a,&b);
		memset(s,0,sizeof(s));

		for (int i = 0 ; i < a-b ; i++)
			s[i] = '0' ;
		for (int j = a-b ; j < a ; j++)
			s[j] = '1';
		cout<<s<<endl;

		while (next_permutation(s,s+a))
			 cout<<s<<endl;
		if (t)
			cout<<endl;
	}
	return 0;
}