leetcode146周赛-5130-等价多米诺骨牌对的数量

题目描述：

方法一：

class Solution(object):
    def numEquivDominoPairs(self, dominoes):
        """
        :type dominoes: List[List[int]]
        :rtype: int
        """
        f = {}
        ret = 0
        for d in dominoes:
            if d[0] > d[1]:
                d[0], d[1] = d[1], d[0]
            x = d[0] * 10 + d[1]
            ret += f.get(x, 0)
            f[x] = f.get(x, 0) + 1
        return ret

另：

class Solution:
    def numEquivDominoPairs(self, dominoes: List[List[int]]) -> int:
        hashmap = collections.defaultdict(int)
        for i, j in dominoes:
            if i > j:
                i, j = j, i
            hashmap[(i,j)] += 1
        ans = 0
        for key in hashmap:
            ans += hashmap[key]*(hashmap[key]-1)//2
        return an