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  • 岛屿数量

    问题:

    # 给你一个由 '1'(陆地)和 '0'(水)组成的的二维网格,请你计算网格中岛屿的数量。 
    #
    # 岛屿总是被水包围,并且每座岛屿只能由水平方向和/或竖直方向上相邻的陆地连接形成。
    #
    # 此外,你可以假设该网格的四条边均被水包围。
    #
    #
    #
    # 示例 1:
    #
    #
    # 输入:grid = [
    # ["1","1","1","1","0"],
    # ["1","1","0","1","0"],
    # ["1","1","0","0","0"],
    # ["0","0","0","0","0"]
    # ]
    # 输出:1

    方法:dfs,bfs,并查集

    # leetcode submit region begin(Prohibit modification and deletion)
    class Solution:
        def numIslands(self, grid: List[List[str]]) -> int:
            if not grid or not grid[0]:
                return 0
            m, n = len(grid), len(grid[0])
            count = 0
    
            def dfs(i, j):
                # 数据抹零
                grid[i][j] = '0'
                # 查找上下左右
                for dx, dy in [[1, 0], [-1, 0], [0, 1], [0, -1]]:
                    x, y = i + dx, j + dy
                    if 0 <= x < m and 0 <= y < n and grid[x][y] == '1':
                        dfs(x, y)
            for i in range(m):
                for j in range(n):
                    if grid[i][j] == '1':
                        count += 1
                        dfs(i, j)
            return count
    # leetcode submit region end(Prohibit modification and deletion)
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  • 原文地址:https://www.cnblogs.com/demo-deng/p/14815505.html
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