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.

Sum Problem

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

解题思路:很简单，求累加和。然而我提交了9次才AC了两次。

代码如下

第一次AC

#include <stdio.h>

int sso(int n);
int main(void)
{
    int i;
    while (scanf_s("%d", &i) != EOF)
    {
        printf("%d\n",sso(i));
        putchar(‘\n‘);
    }
        return 0;
}
int sso(int n)
{
    int i, sum=0;
    for (i = 0; i <= n; i++)
        sum += i;

    return sum;
}第二次AC

#include <stdio.h>
int main(void)
{
    int a = 0, b, sum = 0;
    while (scanf_s("%d", &b) != EOF)
    {
        sum = 0, a = 0;
        do {
            a = a + 1;
            sum = a + sum;
        } while (a<b);
        printf("%d\n", sum);
        printf("\n");
    }
    return 0;
}