CodeForces 768B - Code For 1 分治

#include <bits/stdc++.h>
using namespace std;

unordered_map<long long, long long> Len;

long long GetLen(long long x)
{
if (x <= 1)
return 1;
if (Len.count(x) == 0)
Len[x] = 2 * GetLen(x / 2) + 1;
return Len[x];
}

long long Solve(long long n, long long l, long long r)
{
l = max(l, 0LL);
if (r < l)
return 0;
if (l >= GetLen(n))
return 0;
if (n == 0)
return 0;
if (n == 1)
return 1;
long long a = GetLen(n / 2);
return Solve(n / 2, l, r) + Solve(n % 2, l - a, r - a) + Solve(n / 2, l - a - 1, r - a - 1);
}

int main()
{
long long n, l, r;
cin >> n >> l >> r;
l--, r--;
cout << Solve(n, l, r) << endl;
}