题目:
Given a positive integer num, write a function which returns True if num is a perfect square else False.
Follow up: Do not use any built-in library function such as sqrt.
思路:
我是用的最笨的方法,实际上其背后蕴含着一个数学规律。
代码实现:
class Solution {
public:
bool isPerfectSquare(int num) {
long i = 1;
while (i*i < num){
++i;
}
return i*i == num;
}
};