杭电ACM----------1001 Sum problem

Problem DescriptionHey, welcome to HDOJ(Hangzhou Dianzi University Online Judge).In this problem, your task is to calculate SUM(n) = 1 + 2 + 3 + ... + n. InputThe input will consist of a series of integers n, one integer per line. OutputFor 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 Input1100 Sample Output15050

要解决这样的问题，首先想到的就是递归

int SumN(int n){if(n == 1){return n;}else{return n +　SumN(n - 1);}}