LeetCode Sum of Square Numbers

原题链接在这里：https://leetcode.com/problems/sum-of-square-numbers/description/

题目：

Given a non-negative integer c, your task is to decide whether there're two integers a and b such that a2 + b2 = c.

Example 1:

Input: 5
Output: True
Explanation: 1 * 1 + 2 * 2 = 5 

Example 2:

Input: 3
Output: False

题解：

在[0, (int)Math.sqrt(c)]区间内用two points夹比.

Time Complexity: O(sqrt(c)). Space: O(1).

AC Java:

 class Solution {
     public boolean judgeSquareSum(int c) {
         if(c < 0){
             return false;
         }

         int l = 0;
         int r = (int)Math.sqrt(c);
         while(l<=r){
             int cur = l*l + r*r;
             if(cur == c){
                 return true;
             }else if(cur < c){
                 l++;
             }else if(cur > c){
                 r--;
             }
         }
         return false;
     }
 }