Merge branch 'master' into 1023

Author: havanagrawal

README.md

@@ -27,9 +27,11 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|---------------|---------------|--------|-------------|-------------
+|1030|[Matrix Cells in Distance Order](https://leetcode.com/problems/matrix-cells-in-distance-order/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1030.java) | O(R*C) | O(1) | |Easy|
 |1023|[Camelcase Matching](https://leetcode.com/problems/camelcase-matching/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1023.java)| O(mn) | O(n) | |Medium| String |
 |1022|[Sum of Root To Leaf Binary Numbers](https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1022.java) | O(n) | O(n) | |Easy|
 |1021|[Remove Outermost Parentheses](https://leetcode.com/problems/remove-outermost-parentheses/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1021.java) | O(n) | O(n) | |Easy|
+|1020|[Number of Enclaves](https://leetcode.com/problems/number-of-enclaves/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1020.java) | O(mn) | O(mn) | |Medium|Graph, DFS, BFS, recursion|
 |1018|[Binary Prefix Divisible By 5](https://leetcode.com/problems/binary-prefix-divisible-by-5/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1018.java) | O(n) | O(1) | |Easy|
 |1013|[Pairs of Songs With Total Durations Divisible by 60](https://leetcode.com/problems/pairs-of-songs-with-total-durations-divisible-by-60/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1013.java) | O(n) | O(1) | |Easy|
 |1009|[Complement of Base 10 Integer](https://leetcode.com/problems/complement-of-base-10-integer/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1009.java) | O(n) | O(1) | |Easy|

src/main/java/com/fishercoder/solutions/_1020.java

@@ -0,0 +1,61 @@
+package com.fishercoder.solutions;
+
+/**
+ * 1020. Number of Enclaves
+ *
+ * Given a 2D array A, each cell is 0 (representing sea) or 1 (representing land)
+ *
+ * A move consists of walking from one land square 4-directionally to another land square, or off the boundary of the grid.
+ *
+ * Return the number of land squares in the grid for which we cannot walk off the boundary of the grid in any number of moves.
+ */
+
+public class _1020 {
+    public static class Solution1 {
+        public void walk(int[][] A, boolean[][] visited, int x, int y) {
+            if (x >= A.length || x < 0 || y >= A[0].length || y < 0) {
+                return;
+            }
+            if (visited[x][y]) {
+                return;
+            }
+            if (A[x][y] == 0) {
+                return;
+            }
+
+            visited[x][y] = true;
+
+            walk(A, visited, x - 1, y);
+            walk(A, visited, x, y - 1);
+            walk(A, visited, x, y + 1);
+            walk(A, visited, x + 1, y);
+        }
+
+        public int numEnclaves(int[][] A) {
+            int n = A.length;
+            int m = A[0].length;
+            boolean[][] visited = new boolean[n][m];
+
+            for (int i = 0; i < n; ++i) {
+                walk(A, visited, i, 0);
+                walk(A, visited, i, m - 1);
+            }
+
+            for (int j = 0; j < m; ++j) {
+                walk(A, visited, 0, j);
+                walk(A, visited, n - 1, j);
+            }
+
+            int unreachables = 0;
+            for (int i = 0; i < n; ++i) {
+                for (int j = 0; j < m; ++j) {
+                    if (A[i][j] == 1 && !visited[i][j]) {
+                        ++unreachables;
+                    }
+                }
+            }
+
+            return unreachables;
+        }
+    }
+}

src/main/java/com/fishercoder/solutions/_1030.java

@@ -0,0 +1,69 @@
+package com.fishercoder.solutions;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+/**
+ * 1030. Matrix Cells in Distance Order
+ *
+ * We are given a matrix with R rows and C columns has cells with integer coordinates (r, c), where 0 <= r < R and 0 <= c < C.
+ *
+ * Additionally, we are given a cell in that matrix with coordinates (r0, c0).
+ *
+ * Return the coordinates of all cells in the matrix, sorted by their distance from (r0, c0) from smallest distance to largest distance.  Here, the distance between two cells (r1, c1) and (r2, c2) is the Manhattan distance, |r1 - r2| + |c1 - c2|.  (You may return the answer in any order that satisfies this condition.)
+ *
+ * Example 1:
+ * Input: R = 1, C = 2, r0 = 0, c0 = 0
+ * Output: [[0,0],[0,1]]
+ * Explanation: The distances from (r0, c0) to other cells are: [0,1]
+ *
+ * Example 2:
+ * Input: R = 2, C = 2, r0 = 0, c0 = 1
+ * Output: [[0,1],[0,0],[1,1],[1,0]]
+ * Explanation: The distances from (r0, c0) to other cells are: [0,1,1,2]
+ * The answer [[0,1],[1,1],[0,0],[1,0]] would also be accepted as correct.
+ *
+ * Example 3:
+ * Input: R = 2, C = 3, r0 = 1, c0 = 2
+ * Output: [[1,2],[0,2],[1,1],[0,1],[1,0],[0,0]]
+ * Explanation: The distances from (r0, c0) to other cells are: [0,1,1,2,2,3]
+ * There are other answers that would also be accepted as correct, such as [[1,2],[1,1],[0,2],[1,0],[0,1],[0,0]].
+ *
+ * Note:
+ *
+ * 1 <= R <= 100
+ * 1 <= C <= 100
+ * 0 <= r0 < R
+ * 0 <= c0 < C
+ * */
+public class _1030 {
+    public static class Solution1 {
+        public int[][] allCellsDistOrder(int R, int C, int r0, int c0) {
+            int[][] result = new int[R * C][2];
+            Queue<int[]> queue = new LinkedList<>();
+            queue.offer(new int[]{r0, c0});
+            boolean[][] visited = new boolean[R][C];
+            int i = 0;
+            while (!queue.isEmpty()) {
+                int[] cell = queue.poll();
+                int row = cell[0];
+                int col = cell[1];
+
+                if (row < 0 || row >= R || col < 0 || col >= C || visited[row][col]) {
+                    continue;
+                }
+
+                visited[row][col] = true;
+                result[i++] = new int[]{row, col};
+                queue.offer(new int[]{row, col + 1});
+                queue.offer(new int[]{row + 1, col});
+                queue.offer(new int[]{row - 1, col});
+                queue.offer(new int[]{row, col - 1});
+
+            }
+            return result;
+        }
+    }
+}

src/test/java/com/fishercoder/_1020Test.java

@@ -0,0 +1,54 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1020;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1020Test {
+    private static _1020.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1020.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        int[][] map = {
+                {0, 0, 0, 0},
+                {1, 0, 1, 0},
+                {0, 1, 1, 0},
+                {0, 0, 0, 0}
+        };
+
+        assertEquals(solution1.numEnclaves(map), 3);
+    }
+
+    @Test
+    public void test2() {
+        int[][] map = {
+                {0, 1, 1, 0},
+                {0, 0, 1, 0},
+                {0, 0, 1, 0},
+                {0, 0, 0, 0}
+        };
+
+        assertEquals(solution1.numEnclaves(map), 0);
+    }
+
+    @Test
+    public void test3() {
+        int[][] map = {
+                {0, 1, 1, 0},
+                {0, 0, 0, 0},
+                {1, 0, 1, 0},
+                {1, 0, 0, 0},
+                {0, 1, 1, 0},
+                {0, 0, 0, 0},
+        };
+
+        assertEquals(solution1.numEnclaves(map), 3);
+    }
+}

src/test/java/com/fishercoder/_1030Test.java

@@ -0,0 +1,31 @@
+package com.fishercoder;
+
+import com.fishercoder.common.utils.CommonUtils;
+import com.fishercoder.solutions._1030;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class _1030Test {
+    private static _1030.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1030.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        CommonUtils.print2DIntArray(solution1.allCellsDistOrder(1, 2, 0, 0));
+    }
+
+    @Test
+    public void test2() {
+        CommonUtils.print2DIntArray(solution1.allCellsDistOrder(2, 2, 0, 1));
+    }
+
+    @Test
+    public void test3() {
+        CommonUtils.print2DIntArray(solution1.allCellsDistOrder(2, 3, 1, 2));
+    }
+
+}