#79

Word Search

medium· Backtrackingruns: 0

Given an m x n grid of characters board and a string word, return true if word exists in the grid. The word can be constructed from sequentially adjacent cells (horizontally or vertically) where the same cell may not be used more than once.

wpm 0acc 100%time 0:000 / 903

class Solution:
    def exist(self, board: list[list[str]], word: str) -> bool:
        rows, cols = len(board), len(board[0])

        def dfs(r: int, c: int, i: int) -> bool:
            if i == len(word):
                return True
            if (
                r < 0
                or r >= rows
                or c < 0
                or c >= cols
                or board[r][c] != word[i]
            ):
                return False
            tmp = board[r][c]
            board[r][c] = "#"
            found = (
                dfs(r + 1, c, i + 1)
                or dfs(r - 1, c, i + 1)
                or dfs(r, c + 1, i + 1)
                or dfs(r, c - 1, i + 1)
            )
            board[r][c] = tmp
            return found

        for r in range(rows):
            for c in range(cols):
                if dfs(r, c, 0):
                    return True
        return False

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