@@ -282,6 +282,71 @@ class Solution {
282282}
283283```
284284
285+ ### Python
286+ 287+ ``` python
288+ 289+ class Solution :
290+ def largestIsland (self grid : List[List[int ]]) -> int :
291+ visited = set () # 标记访问过的位置
292+ m, n = len (grid), len (grid[0 ])
293+ res = 0
294+ island_size = 0 # 用于保存当前岛屿的尺寸
295+ directions = [[0 , 1 ], [0 , - 1 ], [1 , 0 ], [- 1 , 0 ]] # 四个方向
296+ islands_size = defaultdict(int ) # 保存每个岛屿的尺寸
297+ 298+ def dfs (island_num , r , c ):
299+ visited.add((r, c))
300+ grid[r][c] = island_num # 访问过的位置标记为岛屿编号
301+ nonlocal island_size
302+ island_size += 1
303+ for i in range (4 ):
304+ nextR = r + directions[i][0 ]
305+ nextC = c + directions[i][1 ]
306+ if (nextR not in range (m) or # 行坐标越界
307+ nextC not in range (n) or # 列坐标越界
308+ (nextR, nextC) in visited): # 坐标已访问
309+ continue
310+ if grid[nextR][nextC] == 1 : # 遇到有效坐标,进入下一个层搜索
311+ dfs(island_num, nextR, nextC)
312+ 313+ island_num = 2 # 初始岛屿编号设为2, 因为grid里的数据有0和1, 所以从2开始编号
314+ all_land = True # 标记是否整个地图都是陆地
315+ for r in range (m):
316+ for c in range (n):
317+ if grid[r][c] == 0 :
318+ all_land = False # 地图里不全是陆地
319+ if (r, c) not in visited and grid[r][c] == 1 :
320+ island_size = 0 # 遍历每个位置前重置岛屿尺寸为0
321+ dfs(island_num, r, c)
322+ islands_size[island_num] = island_size # 保存当前岛屿尺寸
323+ island_num += 1 # 下一个岛屿编号加一
324+ if all_land:
325+ return m * n # 如果全是陆地, 返回地图面积
326+ 327+ count = 0 # 某个位置0变成1后当前岛屿尺寸
328+ # 因为后续计算岛屿面积要往四个方向遍历,但某2个或3个方向的位置可能同属于一个岛,
329+ # 所以为避免重复累加,把已经访问过的岛屿编号加入到这个集合
330+ visited_island = set () # 保存访问过的岛屿
331+ for r in range (m):
332+ for c in range (n):
333+ if grid[r][c] == 0 :
334+ count = 1 # 把由0转换为1的位置计算到面积里
335+ visited_island.clear() # 遍历每个位置前清空集合
336+ for i in range (4 ):
337+ nearR = r + directions[i][0 ]
338+ nearC = c + directions[i][1 ]
339+ if nearR not in range (m) or nearC not in range (n): # 周围位置越界
340+ continue
341+ if grid[nearR][nearC] in visited_island: # 岛屿已访问
342+ continue
343+ count += islands_size[grid[nearR][nearC]] # 累加连在一起的岛屿面积
344+ visited_island.add(grid[nearR][nearC]) # 标记当前岛屿已访问
345+ res = max (res, count)
346+ return res
347+ 348+ ```
349+ 285350<p align =" center " >
286351<a href =" https://programmercarl.com/other/kstar.html " target =" _blank " >
287352 <img src =" ../pics/网站星球宣传海报.jpg " width =" 1000 " />
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