1001---Sum Problem

http://acm.hdu.edu.cn/showproblem.php?pid=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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两种方法：

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

 

#include <stdio.h>
int sum(int);

int main(){
    int input,output;
    while (scanf("%d",&input)==1)
    {
        output = sum(input);
        printf("%d\n\n",output);
    }
    return 0;
}
int sum(int n){
    int sum,i;
    sum=0;
    for (i=1;i<=n;i++)
    {
        sum+=i;
    }
    return sum;
}