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;
    }
}