1363 - Joseph's Problem

#include<iostream>
#include<vector>
#include<string>
#include<set>
#include<stack>
#include<queue>
#include<map>
#include<algorithm>
#include<cmath>
#include<iomanip>
#include<cstring>
#include<sstream>
#include<cstdio>
#include<deque>
#include<functional>
using namespace std;

typedef long long LL;

long long  getRes(int total,int q,int p){
int first = q;
int last = q - total*p;
return (long long)(first + last)*(total+1) / 2;
}

int main(){
int n, k;
while (cin >> n >> k){
int i = 1;
int cnt = 0;
LL ans = 0;
while (i <= n){
int p = k / i, q = k%i;
cnt = n - i;
if(p>0) cnt = min(cnt, q / p);
ans += getRes(cnt, q, p);
i += cnt+1;
}
cout << ans << endl;
}
return 0;
}