HDU计算机学院大学生程序设计竞赛（2015’12）1005 Bitwise Equations

#include<cstdio>
#include<cstring>
#include<string>
#include<iostream>
#include<algorithm>
#include<map>
using namespace std;
const int N=50005;
int n,k;
int seg[66],v[66];
long long m[66];
int main()
{
    int i,j,r;
    m[0]=1;
    for(i=1;i<=64;i++)
        m[i]=m[i-1]*2;
    int T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d%d",&n,&k);
        long long ans=0;
        k;
        int cnt=0;
        memset(v,0,sizeof(v));
        for(i=1;i<=63;i++)
        {
            seg[i]=n%2;
            n/=2;
            if(seg[i]==0) v[i]=++cnt;
        }
        for(i=63;i>=1;i--)
        {
            if(v[i]==0) continue;
            if(k>=m[v[i]-1]) ans+=m[i-1],k-=m[v[i]-1];
        }
        cout<<ans<<endl;


    }
    return 0;
}