POJ 3252 Round Numbers

RT.

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int l,r,dp[33][33][33],ret=0,bit[33];
void get_bit(int x)
{
    ret=0;
    while (x) {bit[++ret]=(x&1);x>>=1;}
}
int dfs(int pos,int cnt1,int cnt2,bool flag)
{
    if (!pos) return cnt1>=cnt2;
    if ((!flag) && (~dp[pos][cnt1][cnt2])) return dp[pos][cnt1][cnt2];
    int ans=0,up=flag?bit[pos]:1;
    for (int i=0;i<=up;i++)
    {
        if (i&1) ans+=dfs(pos-1,cnt1,cnt2+1,flag&&i==up);
        else ans+=dfs(pos-1,cnt1+1,cnt2,flag&&i==up);
    }
    if (!flag) dp[pos][cnt1][cnt2]=ans;
    return ans;
}
int work(int x)
{
    get_bit(x);int ans=0;
    for (int i=1;i<=ret-1;i++) ans+=dfs(i-1,0,1,0);
    ans+=dfs(ret-1,0,1,1);
    return ans;
}
int main()
{
    memset(dp,-1,sizeof(dp));
    scanf("%d%d",&l,&r);
    printf("%d
",work(r)-work(l-1));
    return 0;
}