LeetCode 367.有效的完全平方数（简单）

python

1.普通解法

class Solution:
    def isPerfectSquare(self, num: int) -> bool:
        if num==1:
            return True
        for i in range(1,num//2+1):
            if(i*i == num):
                return True
            elif (i*i>num):
                break

        return False

2.二分法：

class Solution:
    def isPerfectSquare(self, num: int) -> bool:
        # if num==1:
        #     return True
        # for i in range(1,num//2+1):
        #     if(i*i == num):
        #         return True
        #     elif (i*i>num):
        #         break

        # return False

        left = 0
        right = num//2 + 1
        while(left <= right):
            mid = (left+right)//2
            if(mid*midnum):
                right = mid - 1
            else:
                return True
        
        return False