"""
岛屿的周长
"""
from typing import List


class Solution:
    def islandPerimeter(self, grid: List[List[int]]) -> int:
        # x轴和y轴
        directions = [[0, 1], [0, -1], [1, 0], [-1, 0]]
        result = 0
        for i in range(len(grid)):
            for j in range(len(grid[0])):
                # 如果是水域直接跳过,只处理岛屿的格子
                if grid[i][j] == 1:
                    # 存在岛屿则重置
                    count = 0
                    # 计算每个岛屿右左上下是否有水域或者是边界
                    for x, y in directions:
                        ix = i + x
                        jy = j + y
                        # 和岛屿连接的水域边,针对的是当前行的加减,当前行的坐标小于0或者大于等于最大index则说明是在边界
                        if ix < 0 or ix >= len(grid) or jy < 0 or jy >= len(grid[0]) or grid[ix][jy] == 0:
                            count += 1
                    result += count
        return result


if __name__ == '__main__':
    result = Solution().islandPerimeter([[0, 1, 0, 0], [1, 1, 1, 0], [0, 1, 0, 0], [1, 1, 0, 0]])
    print(result)