hdu Round Numbers 找一个范围数中（二进制），0的个数比1大的数的个数

Problem Description

The cows, as you know, have no fingers or thumbs and thus are unable to play Scissors, Paper, Stone' (also known as 'Rock, Paper, Scissors', 'Ro, Sham, Bo', and a host of other names) in order to make arbitrary decisions such as who gets to be milked first. They can't even flip a coin because it's so hard to toss using hooves.

They have thus resorted to "round number" matching. The first cow picks an integer less than two billion. The second cow does the same. If the numbers are both "round numbers", the first cow wins,
otherwise the second cow wins.

A positive integer N is said to be a "round number" if the binary representation of N has as many or more zeroes than it has ones. For example, the integer 9, when written in binary form, is 1001. 1001 has two zeroes and two ones; thus, 9 is a round number. The integer 26 is 11010 in binary; since it has two zeroes and three ones, it is not a round number.

Obviously, it takes cows a while to convert numbers to binary, so the winner takes a while to determine. Bessie wants to cheat and thinks she can do that if she knows how many "round numbers" are in a given range.

Help her by writing a program that tells how many round numbers appear in the inclusive range given by the input (1 ≤ Start < Finish ≤ 2,000,000,000).

 

Input

Line 1: Two space-separated integers, respectively Start and Finish.

 

Output

Line 1: A single integer that is the count of round numbers in the inclusive range Start..Finish

 

Sample Input

2 12

 

Sample Output

6

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组合数学

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#include<iostream>
#include<cstdio>
#include<ctime>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<cstdlib>
#include<vector>
#define C    240
#define TIME 10
#define inf 1<<25
#define LL long long
using namespace std;
int c[35][35];
void init(){
    for(int i=0;i<33;i++){
        c[i][0]=c[i][i]=1;
        for(int j=1;j<i;j++)
            c[i][j]=c[i-1][j]+c[i-1][j-1];
    }
}
int slove(int n){
    int len=0,bit[35];
    while(n){
        bit[++len]=n&1;
        n>>=1;
    }
    int sum=0;
    for(int i=1;i<len;i++)//先枚举最高位为0的
        for(int j=(i+1)/2;j<i;j++)
            sum+=c[i-1][j];
    int one=1,zero=0;
    for(int i=len-1;i;i--){
        if(bit[i]){//如果高位为1，则可随便枚举，只要满足条件
            zero++;
            for(int j=max(0,(len+1)/2-zero);j<i;j++)
                sum+=c[i-1][j];
            zero--;
            one++;
        }
        else
            zero++;
    }
    return sum;
}
int main(){
    int le,ri;
    init();
    while(cin>>le>>ri)
        cout<<slove(ri+1)-slove(le)<<endl;
    return 0;
}