杭电oj 1001

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

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#include<iostream>
using namespace std;
int main()
{
    int a,n,sum;
    while(cin>>a)
    {
        sum=0;
        for(n=1;n<=a;n++)
        {
            sum=sum+n;
        }
        cout<<sum<<endl<<endl;
    }
    return 0;
}

这里有个很无聊的小陷阱，“ followed by a blank line”（然后再输出空白行）。

来源：https://blog.csdn.net/haolovejin/article/details/101114341