LightOJ 1042 - Secret Origins

http://www.lightoj.com/volume_showproblem.php?problem=1042

代码:

#include<cstdio>
#include<cstring>
#include<iostream>
#include<cmath>
#include<string>
#include<vector>
#include<map>
using namespace std;
int Rint() { int x; scanf("%d", &x); return x; }
#define FOR(i, a, b) for(int i=(a); i<(b); i++)
#define REP(x) for(int i=0; i<(x); i++)
#define int64 long long
#define INF 1<<30
#define bug(s) cout<<#s<<"="<<s

//	低位的一个01组合,变为10.	 更低位的1全移到最末

int BitCount(unsigned int n) 
{ 
    n = (n & 0x55555555) + ((n >> 1) & 0x55555555) ; 
    n = (n & 0x33333333) + ((n >> 2) & 0x33333333) ; 
    n = (n & 0x0f0f0f0f) + ((n >> 4) & 0x0f0f0f0f) ; 
    n = (n & 0x00ff00ff) + ((n >> 8) & 0x00ff00ff) ; 
    n = (n & 0x0000ffff) + ((n >> 16) & 0x0000ffff) ; 
    return n ; 
} 

int solve(int x)
{
	int lowbit = x&(-x);
	int y = (-x)^lowbit;
	int  lowzero = y&(-y);
	int ans = (x|lowzero)^(lowzero>>1);
	int cnt = BitCount((unsigned int)(ans&(lowzero-1)));
	ans = (ans|(lowzero-1))^(lowzero-1);
	ans|=(1<<cnt)-1;
	return ans;
}

int main()
{
	int T = Rint();
	for(int t=0; t<T; t++)
	{
		printf("Case %d: %d\n", t+1, solve(Rint()));
	}
}