#include<bits/stdc++.h> using namespace std; int main(){ long long n,m,s = 0,i,j,x = 0,t; cin>>n>>m; for(i = 1;i <= n;i++){ x += i; } x = x * 2;//一个完整的1 2 3..n n n-1.. 2 1的和 s = m / (2 * n) * x;//先求有多少完整的循环 t = m % (2 * n);//除了完整循环还剩余的数 if(t <= n){ for(i = 1;i <= t;i++){ s = s + i; } } else{ s = s + x / 2;//先加一半的循环的和 for(i = n;i > n - (t - n);i--) { s = s + i; } } cout<<s<<endl; } /************************************************************** Problem: 1536 User: admin Language: C++ Result: Accepted Time:77 ms Memory:2072 kb ****************************************************************/