判断一个数字是否是平方数

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DESCRIPTION

Given an integral number, determine if it’s a square number:

In mathematics, a square number or perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself.

The tests will always use some integral number, so don’t worry about that in dynamic typed languages.

Examples

-1  =>  false
 0  =>  true
 3  =>  false
 4  =>  true
25  =>  true
26  =>  false

SOLUTION

• 方法一：

var isSquare = function (n) {
  // 求平方根并取整
  let roundSqrt = Math.round(Math.sqrt(n));
  // 判断平方根相乘的结果是否与传入的数值相等
  return n === roundSqrt * roundSqrt;
};

• 方法二：

function isSquare(n) {
  return Math.sqrt(n) % 1 === 0;
}

Reference

You’re a square!