Update solution 695 [Java]

Author: yanglbme

README.md

@@ -41,6 +41,7 @@ Complete [solutions](https://github.com/doocs/leetcode/tree/master/solution) to
 | 235 | [Lowest Common Ancestor of a Binary Search Tree](https://github.com/doocs/leetcode/tree/master/solution/235.Lowest%20Common%20Ancestor%20of%20a%20Binary%20Search%20Tree) | `Tree` |
 | 237 | [Delete Node in a Linked List](https://github.com/doocs/leetcode/tree/master/solution/237.Delete%20Node%20in%20a%20Linked%20List) | `Linked List` |
 | 344 | [Reverse String](https://github.com/doocs/leetcode/tree/master/solution/344.Reverse%20String) | `Two Pointers`, `String` |
+| 695 | [Max Area of Island](https://github.com/doocs/leetcode/tree/master/solution/695.Max%20Area%20of%20Island) | `Array`, `Depth-first Search` |
 | 703 | [Kth Largest Element in a Stream](https://github.com/doocs/leetcode/tree/master/solution/703.Kth%20Largest%20Element%20in%20a%20Stream) | `Heap` |
 | 707 | [Design Linked List](https://github.com/doocs/leetcode/tree/master/solution/707.Design%20Linked%20List) | `Linked List`, `Design` |
 | 876 | [Middle of the Linked List](https://github.com/doocs/leetcode/tree/master/solution/876.Middle%20of%20the%20Linked%20List) | `Linked List` |
@@ -101,7 +102,7 @@ I'm looking for long-term contributors/partners to this repo! Send me [PRs](http
 " If you want to go fast, go alone. If you want to go far, go together. And that's the spirit of [teamwork](https://github.com/doocs/leetcode/graphs/contributors) ".
 
 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
-| <center> [<img src="https://avatars3.githubusercontent.com/u/21008209?v=4" width="80px;"/>](https://github.com/yanglbme)<br />[💻](https://github.com/doocs/leetcode/commits?author=yanglbme "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/23625436?v=4" width="80px;"/>](https://github.com/chakyam)<br />[💻](https://github.com/doocs/leetcode/commits?author=chakyam "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/10081554?v=4" width="80px;"/>](https://github.com/zhkmxx9302013)<br />[💻](https://github.com/doocs/leetcode/commits?author=zhkmxx9302013 "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/40383345?v=4" width="80px;"/>](https://github.com/MarkKuang1991)<br />[💻](https://github.com/doocs/leetcode/commits?author=MarkKuang1991 "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/12371194?v=4" width="80px;"/>](https://github.com/fonxian)<br />[💻](https://github.com/doocs/leetcode/commits?author=fonxian "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/25222367?v=4" width="80px;"/>](https://github.com/zhanary)<br />[💻](https://github.com/doocs/leetcode/commits?author=zhanary "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/42396616?v=4" width="80px;"/>](https://github.com/ZhouTingZhaobiu)<br />[💻](https://github.com/doocs/leetcode/commits?author=ZhouTingZhaobiu "Code") </center> | 
-|---|---|---|---|---|---|---|
+| <center> [<img src="https://avatars3.githubusercontent.com/u/21008209?v=4" width="80px;"/>](https://github.com/yanglbme)<br />[💻](https://github.com/doocs/leetcode/commits?author=yanglbme "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/23625436?v=4" width="80px;"/>](https://github.com/chakyam)<br />[💻](https://github.com/doocs/leetcode/commits?author=chakyam "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/10081554?v=4" width="80px;"/>](https://github.com/zhkmxx9302013)<br />[💻](https://github.com/doocs/leetcode/commits?author=zhkmxx9302013 "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/40383345?v=4" width="80px;"/>](https://github.com/MarkKuang1991)<br />[💻](https://github.com/doocs/leetcode/commits?author=MarkKuang1991 "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/12371194?v=4" width="80px;"/>](https://github.com/fonxian)<br />[💻](https://github.com/doocs/leetcode/commits?author=fonxian "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/25222367?v=4" width="80px;"/>](https://github.com/zhanary)<br />[💻](https://github.com/doocs/leetcode/commits?author=zhanary "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/42396616?v=4" width="80px;"/>](https://github.com/ZhouTingZhaobiu)<br />[💻](https://github.com/doocs/leetcode/commits?author=ZhouTingZhaobiu "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/31923541?v=4" width="80px;"/>](https://github.com/zouwx2cs)<br />[💻](https://github.com/doocs/leetcode/commits?author=zouwx2cs "Code") </center> |
+|---|---|---|---|---|---|---|---|
 
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solution/695.Max Area of Island/README.md

@@ -1,11 +1,11 @@
 ## 岛屿的最大面积
 ### 题目描述
 
-给定一个包含了一些 0 和 1的非空二维数组 grid , 一个 岛屿 是由四个方向 (水平或垂直) 的 1 (代表土地) 构成的组合。你可以假设二维矩阵的四个边缘都被水包围着。
+给定一个包含了一些 0 和 1的非空二维数组 `grid` , 一个 岛屿 是由四个方向 (水平或垂直) 的 `1` (代表土地) 构成的组合。你可以假设二维矩阵的四个边缘都被水包围着。
 
 找到给定的二维数组中最大的岛屿面积。(如果没有岛屿，则返回面积为0。)
 
-示例 1:
+**示例 1:**
 ```
 [[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],
@@ -15,21 +15,47 @@
  [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]]
- 
-对于上面这个给定矩阵应返回 6。注意答案不应该是11，因为岛屿只能包含水平或垂直的四个方向的‘1’。
 ```
 
-示例 2:
+对于上面这个给定矩阵应返回 `6`。注意答案不应该是 11，因为岛屿只能包含水平或垂直的四个方向的‘1’。
+
+**示例 2:**
+
 ```
 [[0,0,0,0,0,0,0,0]]
+```
 
-对于上面这个给定的矩阵, 返回 0。
+对于上面这个给定的矩阵, 返回 `0`。
 
-注意: 给定的矩阵grid 的长度和宽度都不超过 50。
-```
+注意: 给定的矩阵 `grid` 的长度和宽度都不超过 50。
 
 ### 解法
-搜索
-
-```
+利用深度优先搜索，遍历矩阵，搜索每个位置上下左右四个方向，若为 1，则累加 1 并将其置为 0 后继续搜索。最后返回最大值。
+
+```java
+class Solution {
+    public int maxAreaOfIsland(int[][] grid) {
+        int res = 0;
+        int m = grid.length;
+        int n = grid[0].length;
+        for (int i = 0; i < m; ++i) {
+            for (int j = 0; j < n; ++j) {
+                res = Math.max(res, dfs(grid, i, j, m, n));
+            }
+        }
+        return res;
+    }
+    
+    private int dfs(int[][] grid, int i, int j, int m, int n) {
+        if (i < 0 || j < 0 || i >= m || j >= n || grid[i][j] == 0) {
+            return 0;
+        }
+        grid[i][j] = 0;
+        return 1 
+            + dfs(grid, i - 1, j, m, n)
+            + dfs(grid, i + 1, j, m, n)
+            + dfs(grid, i, j - 1, m, n)
+            + dfs(grid, i, j + 1, m, n);
+    }
+}
 ```

solution/695.Max Area of Island/Solution.java

@@ -0,0 +1,25 @@
+class Solution {
+    public int maxAreaOfIsland(int[][] grid) {
+        int res = 0;
+        int m = grid.length;
+        int n = grid[0].length;
+        for (int i = 0; i < m; ++i) {
+            for (int j = 0; j < n; ++j) {
+                res = Math.max(res, dfs(grid, i, j, m, n));
+            }
+        }
+        return res;
+    }
+    
+    private int dfs(int[][] grid, int i, int j, int m, int n) {
+        if (i < 0 || j < 0 || i >= m || j >= n || grid[i][j] == 0) {
+            return 0;
+        }
+        grid[i][j] = 0;
+        return 1 
+            + dfs(grid, i - 1, j, m, n)
+            + dfs(grid, i + 1, j, m, n)
+            + dfs(grid, i, j - 1, m, n)
+            + dfs(grid, i, j + 1, m, n);
+    }
+}