【追求进步】求1+2+3+...+n

看着学不懂的网络，脑子都累，最终还是觉得刷算法题目比较舒服！

题目描述

package TestProblem;
public class Test08 {
static int sum,N;
public Test08() {
++N;
sum+=N;
}
public static int Sum_Solution(int n) {
Test08 s=new Test08();
Test08 s1=new Test08();
Test08 s2=new Test08();
return sum;
}
public static void main(String[] args) {
System.out.println(Sum_Solution(3));
}
}

public class Solution {
//java中不能使用一次创建n个对象。只能是递归了
public int Sum_Solution(int n) {
int sum=n;
boolean flag=(n>0)&&((sum+=Sum_Solution(n-1))>0);
return  sum;
}
}