Given a non-empty 2D arraygridof 0's and 1's, anislandis a group of1'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

這道題就是一個簡單的搜尋問題，程式碼比較簡單。

 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