Nearest Exit from Entrance in Maze LeetCode solution in Python

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class Solution:
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    def nearestExit(self, maze: List[List[str]], entrance: List[int]) -> int:
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        x, y = entrance
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        m, n, infi = len(maze), len(maze[0]), int(1e5)
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        reached = lambda p, q: (not p == x or not q == y) and (
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            p == 0 or q == 0 or p == m - 1 or q == n - 1
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        )
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        @lru_cache(None)
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        def dfs(i, j):
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            if i < 0 or j < 0 or i == m or j == n or maze[i][j] == "+":
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                return infi
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            if reached(i, j):
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                return 0
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            maze[i][j] = "+"
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            ans = 1 + min(dfs(i + 1, j), dfs(i - 1, j), dfs(i, j + 1), dfs(i, j - 1))
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            maze[i][j] = "."
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            return ans
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        ans = dfs(x, y)
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        return -1 if ans >= infi else ans