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  • codeforces484A

    Bits

     CodeForces - 484A 

    Let's denote as  the number of bits set ('1' bits) in the binary representation of the non-negative integer x.

    You are given multiple queries consisting of pairs of integers l and r. For each query, find the x, such that l ≤ x ≤ r, and  is maximum possible. If there are multiple such numbers find the smallest of them.

    Input

    The first line contains integer n — the number of queries (1 ≤ n ≤ 10000).

    Each of the following n lines contain two integers li, ri — the arguments for the corresponding query (0 ≤ li ≤ ri ≤ 1018).

    Output

    For each query print the answer in a separate line.

    Examples

    Input
    3
    1 2
    2 4
    1 10
    Output
    1
    3
    7

    Note

    The binary representations of numbers from 1 to 10 are listed below:

    110 = 12

    210 = 102

    310 = 112

    410 = 1002

    510 = 1012

    610 = 1102

    710 = 1112

    810 = 10002

    910 = 10012

    1010 = 10102

    sol:因为二进制一些奇奇怪怪的东西,我们可以得到以下的乱搞,先一位位加上去加到比R大了为止,然后要减到恰好大于等于L,所以尽可能减大的,并没有减过的位

    #include <bits/stdc++.h>
    using namespace std;
    typedef long long ll;
    inline ll read()
    {
        ll s=0;
        bool f=0;
        char ch=' ';
        while(!isdigit(ch))
        {
            f|=(ch=='-'); ch=getchar();
        }
        while(isdigit(ch))
        {
            s=(s<<3)+(s<<1)+(ch^48); ch=getchar();
        }
        return (f)?(-s):(s);
    }
    #define R(x) x=read()
    inline void write(ll x)
    {
        if(x<0)
        {
            putchar('-'); x=-x;
        }
        if(x<10)
        {
            putchar(x+'0');    return;
        }
        write(x/10);
        putchar((x%10)+'0');
        return;
    }
    #define W(x) write(x),putchar(' ')
    #define Wl(x) write(x),putchar('
    ')
    int Q;
    bool Arr[65];
    //const ll a[65]={0,1,3,7,15,31,63,127,255,511,1023,2047,4095,8191,16383,32767,65535,131071,262143,524287,1048575,2097151,4194303,8388607,16777215,33554431,67108863,134217727,268435455,536870911,1073741823,2147483647,4294967295,8589934591,17179869183,34359738367,68719476735,137438953471,274877906943,549755813887,1099511627775,2199023255551,4398046511103,8796093022207,17592186044415,35184372088831,70368744177663,140737488355327,281474976710655,562949953421311,1125899906842623,2251799813685247,4503599627370495,9007199254740991,18014398509481983,36028797018963967,72057594037927935,144115188075855871,288230376151711743,576460752303423487,1152921504606846975,2305843009213693951};
    int main()
    {
        int i,j;;
        R(Q);
        while(Q--)
        {
            ll L=read(),R=read(),ans=0,oo=-1;
            for(i=0;ans<R;i++)
            {
                ++oo;
                ans+=(1ll<<(oo));
            }
            memset(Arr,0,sizeof Arr);
            while(ans>R)
            {
                for(j=oo;~j;j--) if(!Arr[j])
                {
                    if(ans-(1ll<<j)>=L)
                    {
                        ans-=(1ll<<j); Arr[j]=1; break;
                    }
                }
            }
            Wl(ans);
        }
        return 0;
    }
    /*
    Input
    3
    1 2
    2 4
    1 10
    Output
    1
    3
    7
    */
    View Code
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  • 原文地址:https://www.cnblogs.com/gaojunonly1/p/10737783.html
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