#695 岛屿最大面积

Author: Isaaclot

main/src/DFS_BFS/LC_695_AaxAreaOfIsland.java

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+package DFS_BFS;
+
+/**
+ * @author liangqian0723@gmail.com
+ * @since 2020/3/16 11:49 AM
+ */
+public class LC_695_AaxAreaOfIsland {
+    int[] dx = new int[]{1, -1, 0, 0};
+    int[] dy = new int[]{0, 0, 1, -1};
+
+    /**
+     * 沉岛解法: 如果一个格子是岛屿，将岛屿沉掉，并遍历该格子前后左右(4通)的格子是否为岛屿，并且沉掉，直到将所有的岛屿都沉了
+     */
+    public int maxAreaOfIsland(int[][] grid) {
+        int maxArea = 0;
+
+        for (int i = 0; i < grid.length; i++) {
+            for (int j = 0; j < grid[0].length; j++) {
+                if (grid[i][j] == 1) {
+                    int hasSink = sink(i, j, grid);
+                    maxArea = Math.max(hasSink, maxArea);
+                }
+            }
+        }
+        return maxArea;
+    }
+
+    private int sink(int i, int j, int[][] grid) {
+        int hasSink = 1;
+        grid[i][j] = 0;
+        for (int k = 0; k < dx.length; ++k) {
+            int m = i + dx[k];
+            int n = j + dy[k];
+            if (m < 0 || m >= grid.length || n < 0 || n >= grid[0].length) {
+                continue;
+            }
+            if (grid[m][n] == 1) {
+                hasSink += sink(m, n, grid);
+            }
+        }
+        return hasSink;
+    }
+
+
+}

main/test/DFS_BFS/LC_695_AaxAreaOfIslandTest.java

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+package DFS_BFS;
+
+import org.junit.Test;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * @author liangqian0723@gmail.com
+ * @since 2020/3/16 11:48 AM
+ */
+public class LC_695_AaxAreaOfIslandTest {
+    @Test
+    public void test_mac_area_of_island() {
+        LC_695_AaxAreaOfIsland aol = new LC_695_AaxAreaOfIsland();
+        assertThat(aol.maxAreaOfIsland(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}
+        }), is(6));
+    }
+}