aboutsummaryrefslogtreecommitdiff
path: root/num_equivalent_domino_pair.py
blob: 6514349fac07012bc25f566163821c3ea49e580b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
# 1128. Number of Equivalent Domino Pairs
from collections import Counter

"""
given a list of 'dominoes', 'dominoes[i] = [a, b]' is equivalent to
'dominoes[j] = [c, d]' if and only if either 'a == c' and 'b == d' or 'a ==
d' and 'b == c'. return the number of pairs '(i, j)' for which '0 <= i < j <
dominoes.length' and 'dominoes[i]' is equivalent to 'dominoes[j]'.
"""


class Solution(object):
    def numEquivDominoPairs(self, dominoes):
        """
        :type dominoes: List[List[int]]
        :rtype: int
        """
        return sum(
            v * (v - 1) / 2
            for v in Counter(tuple(sorted(u)) for u in dominoes).values()
        )


if __name__ == "__main__":
    obj = Solution()
    print(obj.numEquivDominoPairs(dominoes=[[1, 2], [2, 1], [3, 4], [5, 6]]))
    print(obj.numEquivDominoPairs(dominoes=[[1, 2], [1, 2], [1, 1], [1, 2], [2, 2]]))