题目:
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。
来源:力扣(LeetCode)
链接:力扣(LeetCode)官网 - 全球极客挚爱的技术成长平台
示例:
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
示例 2:输入:
grid = [["1","1","0","0","0"],["1","1","0","0","0"],["0","0","1","0","0"],["0","0","0","1","1"] ]
输出:3
解法:
遍历每个点,如果为1,计数+1并把周围相邻的1标记为2。
代码:
class Solution:def numIslands(self, grid: List[List[str]]) -> int:count = 0def infect(r, c):if 0 <= r < len(grid) and 0 <= c < len(grid[0]) and grid[r][c] == '1':grid[r][c] = '2'infect(r + 1, c)infect(r - 1, c)infect(r, c + 1)infect(r, c - 1)for idr, r in enumerate(grid):for idc, c in enumerate(r):if c == '1':infect(idr, idc)count += 1return count