hdu 5491(2015合肥网赛)The Next

题目;http://acm.hdu.edu.cn/showproblem.php?pid=5491

题意就是,T组测试数据。然后L，S1，S2。L的二进制中有x个1，x满足  S1<=x<=S2

求满足S1<=x<=S2

直接暴力,但是有个地方要注意,当L在递增枚举的过程中,X小于S1的时候,将其二进制中S1-X个0位转化成1,不然会超时

#include<cstdio>
using namespace std;
typedef long long ll;
int main()
{
    ll t,ans=1,a[31],n,s1,s2;
    ll i,sum;
    scanf("%I64d",&t);
    while (t--)
    {
        scanf("%I64d %I64d %I64d",&n,&s1,&s2);
        int flag=0;
        while (1)
        {
            n++;
            ll e=n;
            i=0,sum=0;
            while (e)
            {
                a[++i]=e%2;
                if (e%2) sum++;
                e/=2;
            }
            if (sum<s1)
            {
                ll q=s1-sum,j,w=0;
                for (j=1;j<=i;j++)
                {
                    if (!a[j])
                    {
                        a[j]=1;
                        w++;
                    }
                    if (w==q) break;
                }
                break;
            }
            if (sum<=s2&&sum>=s1)
            {
                flag=1;
                break;
            }
        }
        printf("Case #%I64d: ",ans++);
        if (flag==1) printf("%I64d
",n);
        else
        {
            sum=0;ll x=1;
            for (ll j=1;j<=i;j++)
            {
                sum+=x*a[j];
                x*=2;
            }
            printf("%I64d
",sum);
        }
    }
    return 0;
}