633. Sum of Square Numbers

Description

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

 

Example 1:

Input: c = 5
Output: true
Explanation: 1 * 1 + 2 * 2 = 5

Example 2:

Input: c = 3
Output: false

 

Constraints:

• 0 <= c <= 231 - 1

 

Solutions

Solution: Two Pointers

• Time complexity: O(Math.sqrt(c))
• Space complexity: O(1)

 

JavaScript

/**
 * @param {number} c
 * @return {boolean}
 */
const judgeSquareSum = function (c) {
  let left = 0;
  let right = Math.floor(Math.sqrt(c));

  while (left <= right) {
    const sum = left ** 2 + right ** 2;

    if (sum === c) return true;
    sum > c ? (right -= 1) : (left += 1);
  }
  return false;
};