solves matrix cells in distance order

Author: anishLearnsToCode

README.md

@@ -279,7 +279,7 @@
 | 1022 | [Sum of Root to Leaf Binary Numbers](https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers)                                               |                                                      [![Java](assets/java.png)](src/SumOfRootToLeafBinaryNumbers.java)                                                      |                                                                                                                                   |
 | 1025 | [Divisor Game](https://leetcode.com/problems/divisor-game)                                                                                           |                                                              [![Java](assets/java.png)](src/DivisorGame.java)                                                               |                                                                                                                                   |
 | 1029 | [Two City Scheduling](https://leetcode.com/problems/two-city-scheduling)                                                                             |                                                                                                                                                                             |                                                                                                                                   |
-| 1030 | [Matrix Cells in Distance Order](https://leetcode.com/problems/matrix-cells-in-distance-order)                                                       |                                                                                                                                                                             |                                                                                                                                   |
+| 1030 | [Matrix Cells in Distance Order](https://leetcode.com/problems/matrix-cells-in-distance-order)                                                       |                                                       [![Java](assets/java.png)](src/MatrixCellsInDistanceOrder.java)                                                       |                                                                                                                                   |
 | 1033 | [Moving Stones Until Consecutive](https://leetcode.com/problems/moving-stones-until-consecutive)                                                     |                                                                                                                                                                             |                                                                                                                                   |
 | 1037 | [Valid Boomerang](https://leetcode.com/problems/valid-boomerang)                                                                                     |                                                                                                                                                                             |                                                                                                                                   |
 | 1042 | [Flower Planting with no Adjacent](https://leetcode.com/problems/flower-planting-with-no-adjacent)                                                   |                                                                                                                                                                             |                                                                                                                                   |

src/MatrixCellsInDistanceOrder.java

@@ -0,0 +1,26 @@
+import java.util.LinkedList;
+import java.util.Queue;
+
+public class MatrixCellsInDistanceOrder {
+    public int[][] allCellsDistOrder(final int rows, final int columns, int rCenter, int cCenter) {
+        int[][] result = new int[rows * columns][2];
+        final Queue<int[]> positions = new LinkedList<>();
+        final boolean[][] visited = new boolean[rows][columns];
+        positions.add(new int[] {rCenter, cCenter});
+        int k = 0, row, column;
+        while (!positions.isEmpty()) {
+            int[] position = positions.poll();
+            row = position[0];
+            column = position[1];
+            if (row < 0 || row >= rows || column < 0 || column >= columns) continue;
+            if (visited[row][column]) continue;
+            visited[row][column] = true;
+            result[k++] = position;
+            positions.add(new int[] {row - 1, column});
+            positions.add(new int[] {row, column + 1});
+            positions.add(new int[] {row + 1, column});
+            positions.add(new int[] {row, column - 1});
+        }
+        return result;
+    }
+}