Valid Perfect Square

description

Given a positive integer num, write a function which returns True if num is a perfect square else False.

Note: Do not use any built-in library function such as sqrt().

Example 1:
Input: 16
Returns: True

Example 2:
Input: 14
Returns: False

thinking

使用分数指数次幂的方法，求num的0.5次幂，实际上就是做了sqrt

solution

class Solution {  public:      bool isPerfectSquare(int num)     {          return (int)(pow(num, 0.5)) == pow(num, 0.5) ? true : false;      }  };