洛谷 P2431 正妹吃月饼

P2431 正妹吃月饼

求l到r之间有多少个二进制1

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #define LL long long
 5 using namespace std;
 6 LL ans;
 7 char ch;
 8 inline void read(LL &now)
 9 {
10     int f=1; ch=getchar(); now=0;
11     while(ch>'9'||ch<'0') {if(ch=='-') f*=-1; ch=getchar();}
12     while(ch>='0'&&ch<='9') now=now*10+ch-'0',ch=getchar();
13     now*=f;
14 }
15 
16 int main()
17 {
18     LL l,r;
19     read(l); read(r);
20     while((l|(l+1))<=r) l|=l+1;
21     while(l)
22     {
23         ans+=l&1;
24         l>>=1;
25     }
26     cout<<ans<<endl;
27     return 0;
28 }