[N-0] add 695

Author: fishercoder1534

README.md

@@ -22,6 +22,7 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Difficulty  | Tag          | Notes
 |-----|----------------|---------------|---------------|---------------|-------------|--------------|-----
+|695|[Max Area of Island](https://leetcode.com/problems/max-area-of-island/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_695.java) | O(m*n) | O(1) | Easy | DFS
 |693|[Binary Number with Alternating Bits](https://leetcode.com/problems/binary-number-with-alternating-bits/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_693.java) | O(n) | O(1) | Easy | 
 |690|[Employee Importance](https://leetcode.com/problems/employee-importance/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_690.java) | O(n) | O(h) | Easy | DFS
 |688|[Knight Probability in Chessboard](https://leetcode.com/problems/knight-probability-in-chessboard/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_688.java) | O(n^2) | O(n^2) | Medium | DP

src/main/java/com/fishercoder/solutions/_695.java

@@ -0,0 +1,66 @@
+package com.fishercoder.solutions;
+
+/**
+ * 695. Max Area of Island
+ *
+ * Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1'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.)
+
+ Example 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],
+ [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]]
+
+ Given the above grid, return 6. Note the answer is not 11, because the island must be connected 4-directionally.
+
+ Example 2:
+
+ [[0,0,0,0,0,0,0,0]]
+
+ Given the above grid, return 0.
+
+ Note: The length of each dimension in the given grid does not exceed 50.
+ */
+
+public class _695 {
+
+    public int maxAreaOfIsland(int[][] grid) {
+        if (grid == null || grid.length == 0) {
+            return 0;
+        }
+        int m = grid.length;
+        int n = grid[0].length;
+        int max = 0;
+        for (int i = 0; i < m; i++) {
+            for (int j = 0; j < n; j++) {
+                if (grid[i][j] == 1) {
+                    int area = dfs(grid, i, j, m, n, 0);
+                    max = Math.max(area, max);
+                }
+            }
+        }
+        return max;
+    }
+
+    int dfs(int[][] grid, int i, int j, int m, int n, int area) {
+        if (i < 0 || i >= m || j < 0 || j >= n || grid[i][j] == 0) {
+            return area;
+        }
+        grid[i][j] = 0;
+        area++;
+        area = dfs(grid, i + 1, j, m, n, area);
+        area = dfs(grid, i, j + 1, m, n, area);
+        area = dfs(grid, i - 1, j, m, n, area);
+        area = dfs(grid, i, j - 1, m, n, area);
+        return area;
+    }
+
+}

src/test/java/com/fishercoder/_695Test.java

@@ -0,0 +1,33 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._695;
+import org.junit.Before;
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class _695Test {
+    private static _695 test;
+    private static int[][] grid;
+
+    @Before
+    public void setup() {
+        test = new _695();
+    }
+
+    @Test
+    public void test1() {
+        grid = new int[][]{
+                {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}
+        };
+        assertEquals(6, test.maxAreaOfIsland(grid));
+    }
+
+}