Jon fought bravely to rescue the wildlings who were attacked by the white-walkers at Hardhome. On his arrival, Sam tells him that he wants to go to Oldtown to train at the Citadel to become a maester, so he can return and take the deceased Aemon's place as maester of Castle Black. Jon agrees to Sam's proposal and Sam sets off his journey to the Citadel. However becoming a trainee at the Citadel is not a cakewalk and hence the maesters at the Citadel gave Sam a problem to test his eligibility.
Initially Sam has a list with a single element n. Then he has to perform certain operations on this list. In each operation Sam must remove any element x, such that x > 1, from the list and insert at the same position , , sequentially. He must continue with these operations until all the elements in the list are either 0 or 1.
Now the masters want the total number of 1s in the range l to r (1-indexed). Sam wants to become a maester but unfortunately he cannot solve this problem. Can you help Sam to pass the eligibility test?
The first line contains three integers n, l, r (0 ≤ n < 250, 0 ≤ r - l ≤ 105, r ≥ 1, l ≥ 1) – initial element and the range l to r.
It is guaranteed that r is not greater than the length of the final list.
Output the total number of 1s in the range l to r in the final sequence.
7 2 5
4
10 3 10
5
Consider first example:
Elements on positions from 2-nd to 5-th in list is [1, 1, 1, 1]. The number of ones is 4.
For the second example:
Elements on positions from 3-rd to 10-th in list is [1, 1, 1, 0, 1, 0, 1, 0]. The number of ones is 5.
题目链接:http://codeforces.com/contest/768/problem/B
分析:二分的模版题!来围观看看!
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n, l, r, s = , ans;
void solve(ll a, ll b, ll l, ll r, ll d)//二分的思想
{
if ( a > b || l > r ) return;
else
{
ll mid = (a+b)/;
if ( r < mid )solve(a,mid-,l,r,d/);
else if ( mid < l )solve(mid+,b,l,r,d/);
else {
ans += d%;
solve(a,mid-,l,mid-,d/);
solve(mid+,b,mid+,r,d/);
}
}
}
int main()
{
cin >> n >> l >> r;
long long p = n;
while ( p >= )
{
p /= ;
s = s*+;
}
solve(,s,l,r,n);
cout << ans << endl;
return ;
}