class Solution:
def maxAreaOfIsland(self, grid: List[List[int]]) -> int:
if not grid:
return 0
m = len(grid)
n = len(grid[0])
dirs = [[0, 1], [1, 0], [0, -1], [-1, 0]]
visited = [[False] * n for _ in range(m)]
res = 0
for i in range(m):
for j in range(n):
if not visited[i][j] and grid[i][j] == 1:
self.count = 0 # 注意这里如果不用self, 直接递归里传值会一直是0. 因为是Immutable
# 或者结果在递归间的传递: https://algo.monster/liteproblems/695
self.dfs(grid, i, j, dirs, visited, m, n)
res = max(res, self.count)
return res
def dfs(self, grid, i, j, dirs, visited, m, n):
if visited[i][j] or grid[i][j] == 0:
return
visited[i][j] = True
self.count += 1
for dir in dirs:
ni = i + dir[0]
nj = j + dir[1]
if 0 <= ni < m and 0 <= nj < n:
self.dfs(grid, ni, nj, dirs, visited, m, n)