Coloring A Border LeetCode solution in Python

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# Runtime: 136 ms (Top 91.96%) | Memory: 14.4 MB (Top 28.67%)
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class Solution:
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    def colorBorder(
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        self, grid: List[List[int]], row: int, col: int, color: int
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    ) -> List[List[int]]:
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        rows, cols = len(grid), len(grid[0])
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        border_color = grid[row][col]
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        border = []
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        # Check if a node is a border node or not
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        def is_border(r, c):
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            if r == 0 or r == rows - 1 or c == 0 or c == cols - 1:
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                return True
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            for dr, dc in [(1, 0), (0, 1), (-1, 0), (0, -1)]:
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                nr, nc = r + dr, c + dc
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                if grid[nr][nc] != border_color:
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                    return True
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            return False
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        def dfs(r, c):
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            if (
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                r < 0
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                or c < 0
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                or r == rows
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                or c == cols
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                or (r, c) in visited
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                or grid[r][c] != border_color
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            ):
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                return
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            visited.add((r, c))
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            if is_border(r, c):
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                border.append((r, c))
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            dfs(r + 1, c)
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            dfs(r - 1, c)
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            dfs(r, c + 1)
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            dfs(r, c - 1)
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        visited = set()
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        dfs(row, col)
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        for r, c in border:
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            grid[r][c] = color
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        return grid