[LeetCode] Valid Perfect Square

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

Credits:
Special thanks to @elmirap for adding this problem and creating all test cases.

不使用sqrt判断一个数是否是完全平方数，

class Solution {
public:
    bool isPerfectSquare(int num) {
        for (int i = 1; i <= num / i; i++)
            if (i * i == num)
                return true;
        return false;
    }
};
// 0ms