LeetCode 岛屿个数问题求解

I found myself not as enthusiastic as before.

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这里使用岛屿下沉的思路来进行计数。
原题目给出的是四周（上下左右，“十”字）都是水则为岛，升级为题为上下左右丿捺（“米”字）。给出解法，只需要按照鉴定岛屿的连通方式输入对应的参数即可：

def n_lands(grid, dx, dy):
    # 利用下沉的思想判断到底有几个岛屿
    n_ = 0
    def sink(i,j):#当前下沉点的坐标
        # 终止条件
        if grid[i][j] == 0:
            return 0 
        grid[i][j] = 0
        for idx in range(len(dx)):
            x = i + dx[idx]
            y = j + dy[idx]
            if len(grid) > x >= 0 and len(grid[i]) > y >=0:
                if grid[x][y] == 0:
                    continue
                sink(x,y)
        return 1

    for i in range(len(grid)):
        for j in range(len(grid[i])):
            if grid[i][j] == 0:
                continue
            n_ += sink(i,j)
    return n_

结果：

if __name__ == '__main__':
   #原问题求解
   dx = [-1,1,0,0] # “十”字连通
   dy = [0,0,-1,1]
   print(n_lands([[1,0,0,1,0],
                  [0,0,1,0,1], 
                  [1,0,0,1,1]], dx, dy)) # 5

“十”字方向 -- 手图

if __name__ == '__main__':
   #升级问题求解
   dx = [-1,1,0,0,1,1,-1,-1] # ”米”字连通
   dy = [0,0,-1,1,-1,1,1,-1]
   print(n_lands([[1,0,0,1,0],
                  [0,0,1,0,1], 
                  [1,0,0,1,1]], dx, dy)) # 3

“米”字方向 -- 手图