POJ3252 Round Numbers

终于一遍就写对了. 第一次没有注意读题导致了一个没有注意到什时候要开始统计.

Code

#include <iostream>
#include <string>
#define int long long
using namespace std;
#define F(i, a, b) for(int i=(a); i<=(b);i++)
#define Fd(i, a, b) for(int i=(a);i>=(b);i--)

int f[60][60][60][3][3];
int num[60];
int dp(int x, int zeros, int ones, int zero, int lim){
	#define rem f[x][zeros][ones][zero][lim]
	if(x==0) {
		if(zeros >= ones){
			return 1;
		}else{
			return 0;
		}
	}
	if( rem != -1 ) return rem;
	int sum = 0; int up = lim ? num[x]:1;
	F(i, 0, up){
		if(i==0){
			if(zero ==0 )
			sum += dp(x-1, zeros + 1, ones, (zero && (i==0)), (lim && (i==up)));
			else sum += dp(x-1, zeros, ones, (zero && (i==0)), (lim && (i==up)));
		}
		else if(i==1) sum += dp(x-1, zeros, ones + 1, (zero && (i==0)), (lim && (i==up)));
	}
	rem = sum;
	return sum;
}

int solve(int x){
	memset(f,-1,sizeof f);
    int pos=0;
    while(x){
        num[++pos]=x%2;
        x/=2;
    }
    return dp(pos,0,0,1,1);
}

signed main(){
	int n, m; cin>>n>>m;
	cout<<solve(m)-solve(n-1)<<endl;
}