LeetCode 914 X Of A Kind In A Deck Of Cards - Easy

914. X Of A Kind In A Deck Of Cards — Easy

Open on LeetCode

Problem

914. X of a Kind in a Deck of Cards -- Easy

In a deck of cards, each card has an integer written on it.

Return true if and only if you can choose X >= 2 such that it is possible to split the entire deck into 1 or more groups of cards, where:

Each group has exactly X cards. All the cards in each group have the same integer.

Example 1: Input: deck = [1,2,3,4,4,3,2,1] Output: true Explanation: Possible partition [1,1],[2,2],[3,3],[4,4].

Example 2: Input: deck = [1,1,1,2,2,2,3,3] Output: false´ Explanation: No possible partition.

Example 3: Input: deck = [1] Output: false Explanation: No possible partition.

Example 4: Input: deck = [1,1] Output: true Explanation: Possible partition [1,1].

Example 5: Input: deck = [1,1,2,2,2,2] Output: true Explanation: Possible partition [1,1],[2,2],[2,2].

Constraints:

1 <= deck.length <= 10^4 0 <= deck[i] < 10^4

Solution

class Solution:
    def hasGroupsSizeX(self, deck):
        counter = collections.Counter(deck)
        # apply reduce:
        return reduce(self.gcd, counter.values()) >= 2
    # greatest common divisor: 
    def gcd(self, a, b):
        while b > 0:
            a, b = b, a % b
        return a