杭电ACM 2051 Bitset

http://acm.hdu.edu.cn/showproblem.php?pid=2051

#include <iostream>
using namespace std;
int main()
{
	int n;
	int a[20];
	while(cin>>n){
		memset(a,0,sizeof(a));
		int i=0;
		while(n!=0){
			a[i]=n%2;
			i++;
			n=n/2;
		}
		for(int j=i-1;j>=0;j--)
			cout<<a[j];
		cout<<endl;
	}
	return 0;
}