求1+2+3+...+n
求1+2+3+...+n
http://www.nowcoder.com/questionTerminal/7a0da8fc483247ff8800059e12d7caf1
public class Solution {
public int Sum_Solution(int n) {
//方法一短路与
/*
int ans = n;
boolean flag = (ans>0) && (ans+=Sum_Solution(n-1))>0;
return ans;*/
//方法二求数组个数
int m = (int)Math.pow(n, 2)+n;
return m>>1;
}
}
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