LeetCode — Number of Equivalent Domino Pairs

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) - that is, one domino can be rotated to be equal to another domino.

Return the number of pairs (i, j) for which 0 <= i < j < dominoes.length, and dominoes[i] is equivalent to dominoes[j].

Example 1:

Input: dominoes = [[1,2],[2,1],[3,4],[5,6]]
Output: 1


  • 1 <= dominoes.length <= 40000
  • 1 <= dominoes[i][j] <= 9


Equivalent Domino Paris solution — Array




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Steven Lu

Steven Lu

Dell Technologies — VxRail Software Engineer 👨‍💻

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