Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.

Find the maximum area of an island in the given 2D array. (If there is no island, the maximum area is 0.)

input:
[[0,0,1,0,0,0,0,1,0,0,0,0,0],
 [0,0,0,0,0,0,0,1,1,1,0,0,0],
 [0,1,1,0,1,0,0,0,0,0,0,0,0],
 [0,1,0,0,1,1,0,0,1,0,1,0,0],
 [0,1,0,0,1,1,0,0,1,1,1,0,0],
 [0,0,0,0,0,0,0,0,0,0,1,0,0],
 [0,0,0,0,0,0,0,1,1,1,0,0,0],
 [0,0,0,0,0,0,0,1,1,0,0,0,0]]
output:
6

这道题就是一个简单的搜索问题，代码比较简单。

 1 class Solution:
 2     def maxAreaOfIsland(self, grid: List[List[int]]) -> int:
 3         maxIsland = 0
 4         for i in range(len(grid)):
 5             for j in range(len(grid[0])):
 6                 if grid[i][j] == 1:
 7                     grid[i][j] = 0
 8                     stack = []
 9                     count = 0
10                     stack.append((i, j))
11                     while len(stack) != 0:
12                         (x, y) = stack.pop()
13                         count += 1
14                         if x - 1 >= 0 and grid[x - 1][y] == 1:
15                             stack.append((x - 1, y))
16                             grid[x - 1][y] = 0
17                         if x + 1 < len(grid) and grid[x + 1][y] == 1:
18                             stack.append((x + 1, y))
19                             grid[x + 1][y] = 0
20                         if y - 1 >= 0 and grid[x][y - 1] == 1:
21                             stack.append((x, y - 1))
22                             grid[x][y - 1] = 0
23                         if y + 1 < len(grid[0]) and grid[x][y + 1] == 1:
24                             stack.append((x, y + 1))
25                             grid[x][y + 1] = 0
26                     if count > maxIsland:
27                         maxIsland = count
28         return maxIsland
29