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🐱(dfs): 695. 岛屿的最大面积

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`@@ -117,4 +117,41 @@ class Solution(object):`
`117`	`117`	`return`
`118`	`118`	`for i in xrange(index, len(nums)):`
`119`	`119`	`self.dfs(target - nums[i], i + 1, tmp_list + [nums[i]], res, nums)`
	`120`	+```
	`121`	`+`
	`122`	`+## 695. 岛屿的最大面积`
	`123`	`+`
	`124`	`+[原题链接](https://leetcode-cn.com/problems/max-area-of-island/)`
	`125`	`+`
	`126`	`+### 深度优先搜索`
	`127`	`+`
	`128`	+设计一个递归函数:输入坐标 `(i, j)`,返回该位置能构成岛屿的最大面积。
	`129`	`+`
	`130`	`+- 如果该位置不是岛屿,返回 0`
	`131`	`+- 如果该位置是岛屿,计算其上下左右位置的面积并相加(此过程不断递归)`
	`132`	`+`
	`133`	+```python
	`134`	`+class Solution:`
	`135`	`+ def maxAreaOfIsland(self, grid: List[List[int]]) -> int:`
	`136`	`+ res = 0`
	`137`	`+ for i in range(len(grid)):`
	`138`	`+ for j in range(len(grid[0])):`
	`139`	`+ res = max(self.dfs(grid, i, j), res)`
	`140`	`+ return res`
	`141`	`+`
	`142`	`+ def dfs(self, grid, i, j):`
	`143`	`+ """`
	`144`	`+ 返回面积`
	`145`	`+ """`
	`146`	`+ if i < 0 or j < 0 or i >= len(grid) or j >= len(grid[0]) or grid[i][j] != 1:`
	`147`	`+ return 0`
	`148`	`+ # 避免重复计算`
	`149`	`+ grid[i][j] = 0`
	`150`	`+ # 是岛屿,面积为 1`
	`151`	`+ ans = 1`
	`152`	`+ # 四个方向`
	`153`	`+ for di, dj in [[0, -1], [0, 1], [-1, 0], [1, 0]]:`
	`154`	`+ # 计算四个方向总面积`
	`155`	`+ ans += self.dfs(grid, i + di, j + dj)`
	`156`	`+ return ans`
`120`	`157`	```

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