1. /**
    2.      * 平方数之和 #633
    3.      * https://leetcode-cn.com/problems/sum-of-square-numbers/submissions/
    4.      * 给定一个非负整数 c ，你要判断是否存在两个整数 a 和 b，使得 a2 + b2 = c
    5.      *
    6.      * 示例一
    7.      * 输入：c = 5 输出：true解释：1 * 1 + 2 * 2 = 5
    8.      * 示例二
    9.      * 输入：输入：c = 3 输出：false
    10.      * 示例三
    11.      * 输入：输入：c = 4 输出：true
    12.      * **/
    14.     function judgeSquareSum(c) {
    15.       if (c < 0) return false;
    16.       let mid = Math.ceil(Math.sqrt(c));
    17.       let left = 0;
    18.       let right = mid;
    19.       while (left <= right) {
    20.         let sum = left * left + right * right
    21.         if (sum === c) {
    22.           return true
    23.         } else if (sum > c) {
    24.           right--
    25.         } else {
    26.           left++
    27.         }
    28.       }
    29.       return false
    30.     }
    32.     console.log(judgeSquareSum(5))