LC-0036 Medium LeetCode

36. Valid Sudoku

Array Hash Table Matrix

Read the full problem statement on LeetCode.

Difficulty: medium Acceptance: 62% Topics: Array, Hash Table, Matrix

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Also on leetcode.ca (community mirror)

Reading material

Arrays & Hashing 12 min Math & Geometry 12 min

Reference solution (spoiler · python)

class Solution:
    def isValidSudoku(self, board: List[List[str]]) -> bool:
        seen = set()

        for i in range(9):
            for j in range(9):
                if board[i][j] != ".":
                    num = board[i][j]
                    if (
                        (i, num) in seen
                        or (num, j) in seen
                        or (i // 3, j // 3, num) in seen
                    ):
                        return False
                    seen.add((i, num))
                    seen.add((num, j))
                    seen.add((i // 3, j // 3, num))

        return True

Solution from kamyu104/LeetCode-Solutions · MIT