#367 - Valid Perfect Square

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Problem Description

Given a positive integer num, return true if num is a perfect square or false otherwise.

A perfect square is an integer that is the square of an integer. In other words, it is the product of some integer with itself.

You must not use any built-in library function, such as sqrt.

Solution

/**
 * @param {number} num
 * @return {boolean}
 */
var isPerfectSquare = function(num) {
  let i = 1;

  while (num > 0) {
    num -= i;
    i += 2;
    if (num === 0) {
      return true;
    }
  }

  return false;
};