hdu1001——Sum Problem

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

代码：

#include <cstdio>
#include <algorithm>
using namespace std;
int main(void){
    int n;
    while(~scanf("%d",&n)){
        int res=0;
        for(int i=1;i<=n;i++){
            res+=i;
        }
        printf("%d\n\n",res);
    }
    return 0;
}