leetcode-5.8[367. 有效的完全平方數、290. 單詞規律、914. 卡牌分組]（python實現)

題目1

題解1

class Solution:
    def isPerfectSquare(self, num: int) -> bool:
        """
            二分查找
        """
        if num < 2:
            return num
        # 因爲除了1以外的所有有效數的完全平方一定小於等於num//2
        left, right = 2, num//2
        while left <= right:
            mid = (left+right)//2
            guess_squared = mid*mid
            if num < guess_squared:
                right = mid - 1
            elif num > guess_squared:
                left = mid + 1
            else:
                return True
        return False

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題目2

題目2

class Solution:
    def wordPattern(self, pattern: str, str: str) -> bool:
        str = str.split()
        if len(str) != len(pattern):
            return False
        for i in range(len(pattern)):
            for j in range(i,len(pattern)):
                if pattern[i] == pattern[j]:
                    if str[i] != str[j]:
                        return False
                else:
                    if str[i] == str[j]:
                        return False
        return True

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題目3

題解3

class Solution:
    def hasGroupsSizeX(self, deck: List[int]) -> bool:
        """
            最大公約數
        """
        from collections import Counter
        from functools import reduce
        from fractions import gcd
        count = Counter(deck).values()
        return reduce(gcd, count) >= 2

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