Codeforces Round #553 (Div. 2) C. Problem for Nazar 数学

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 const int mod=1e9+7;
 5 ll solve(ll x){
 6     int flag=0;
 7     ll sum=0;
 8     ll sumodd=0,sumeven=0;
 9     ll i;
10     if(x<=0)return 0;
11     for(i=1;;i<<=1){
12         sum+=i;
13         if(sum>x){
14             sum-=i;
15             if(flag==0)sumodd+=(x-sum);
16             else sumeven+=(x-sum);
17             break;
18         }
19         if(flag==0)sumodd+=i;
20         else sumeven+=i;
21         flag^=1;
22     }
23     return ( (sumodd%mod)*(sumodd%mod)+(sumeven+1)%mod*(sumeven%mod))%mod;
24 
25 }
26 int main(){
27     ll l,r;
28 cin>>l>>r;
29 cout<<(solve(r)-solve(l-1)+mod)%mod<<endl;
30 
31     return 0;
32 }