Leetcode/007_closedIsland.py at master · TheSarang/Leetcode · GitHub

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class Solution:
    def closedIsland(self, grid: List[List[int]]) -> int:

        def dfs(grid, i, j):
            if 0 <= i < len(grid) and 0 <= j < len(grid[i]) and grid[i][j] == 0:
                grid[i][j] = -1
                dfs(grid, i + 1, j)
                dfs(grid, i, j + 1)
                dfs(grid, i, j - 1)
                dfs(grid, i - 1, j)

        islands = 0
        for i in range(len(grid)):
            n = len(grid)
            for j in range(len(grid[i])):
                a = len(grid[i])
                if grid[i][j] == 0 and (i==0 or i==n-1) and ((j==0 or j==a-1)):
                    dfs(grid, i, j)
        for i in range(len(grid)):
            for j in range(len(grid[i])):
                if grid[i][j] == 0:
                    dfs(grid, i, j)
                    islands += 1
        return islands