算法设计与编程 累积相加 双指针 简单一次过

赛氪OJ-专注于算法竞赛的在线评测系统 (saikr.com)

#include<bits/stdc++.h>
using namespace std;
#define int long long
int ans;
int sum[110];
signed main()
{

	int n; cin >> n;
	for (int i = 1; i <= n; i++)     //1  2
	{
		for (int j = 1; j <= i; j++) //1  1+2
		{
			sum[i] += j;
		}
	}

	for (int i = 1; i <= n; i++)
	{
		ans += sum[i];
	}
	cout << ans << endl;
	return 0;
}