HUD-1001 Sum Problem【C++练习题】

Sum Problem
Time Limit: 1000/500 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 598018 Accepted Submission(s): 151211

Problem Description

Hey, welcome to HDOJ(Hangzhou Dianzi University Online Judge).

In this problem, your task is to calculate SUM(n) = 1 + 2 + 3 + … + n.

Input

The input will consist of a series of integers n, one integer per line.

Output

For each case, output SUM(n) in one line, followed by a blank line. You may assume the result will be in the range of 32-bit signed integer.

Sample Input

1
100

Sample Output

1

5050

Author

DOOM III

问题链接：
       http://acm.hdu.edu.cn/showproblem.php?pid=1001

问题简述：
       计算a+b

贴上代码↓↓↓

#include <iostream>
using namespace std;

void main()
{
	long long n;
	while (cin >> n)
	{
		cout << (1+n)*n/2 << endl<<endl ;
	}
}