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-rw-r--r--num_equivalent_domino_pair.py27
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+# 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]]))