# 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]]))
