本文以Leetcode中695、岛屿的最大面积题目为基础进行展开(题目)。
DFS实现
class Solution:
def maxAreaOfIsland(self, grid) -> int:
directx = [-1, 1, 0, 0]
directy = [0, 0, -1, 1]
vis = set()
res = 0
def DFS(x, y, area):
for t in range(4):
newx, newy = x + directx[t], y + directy[t]
if -1 < newx < len(grid) and -1 < newy < len(grid[0]) and grid[newx][newy] == 1 and (newx, newy) not in vis:
vis.add((newx, newy))
area += DFS(newx, newy, 1)
return area
for i in range(len(grid)):
for j in range(len(grid[0])):
if grid[i][j] == 1 and (i, j) not in vis:
vis.add((i, j))
res = max(DFS(i, j, 1), res)
return res
BFS实现
class Solution:
def maxAreaOfIsland(self, grid) -> int:
directx = [-1, 1, 0, 0]
directy = [0, 0, -1, 1]
vis = set()
res = 0
for i in range(len(grid)):
for j in range(len(grid[0])):
if grid[i][j] == 1 and (i, j) not in vis:
vis.add((i, j))
stack = [(i, j)]
ans = 1
while len(stack) != 0:
x, y = stack.pop(0)
for t in range(4):
newx, newy = x + directx[t], y + directy[t]
# 判断是否为可以走得通的路径
if -1 < newx < len(grid) and -1 < newy < len(grid[0]) and (newx, newy) not in vis and grid[newx][newy] == 1:
vis.add((newx, newy))
ans += 1
stack.append((newx, newy))
res = max(res, ans)
return res