solves rotate image

anishLearnsToCode · anishLearnsToCode · commit b099583518cc · 2022-01-06T17:20:55.000+01:00
diff --git a/README.md b/README.md
@@ -48,6 +48,7 @@
 |  45  | [Jump Game II](https://leetcode.com/problems/jump-game-ii)                                                                                                |                                                                   [![Java](assets/java.png)](src/JumpGameII.java)                                                                    |                                                                                                                                   |
 |  46  | [Permutations](https://leetcode.com/problems/permutations)                                                                                                |                                                                  [![Java](assets/java.png)](src/Permutations.java)                                                                   |                                                                                                                                   |
 |  47  | [Permutations II](https://leetcode.com/problems/permutations-ii)                                                                                          |                                                                 [![Java](assets/java.png)](src/PermutationsII.java)                                                                  |                                                                                                                                   |
+|  48  | [Rotate Image](https://leetcode.com/problems/rotate-image)                                                                                                |                                                                   [![Java](assets/java.png)](src/RotateImage.java)                                                                   |                                                                                                                                   |
 |  53  | [Maximum SubArray](https://leetcode.com/problems/maximum-subarray)                                                                                        |                                 [![Java](assets/java.png)](src/MaximumSubArray.java) [![Python](assets/python.png)](python/maximum_sum_subarray.py)                                  |                                                                                                                                   |
 |  55  | [Jump Game](https://leetcode.com/problems/jump-game)                                                                                                      |                                                                    [![Java](assets/java.png)](src/JumpGame.java)                                                                     |                                                                                                                                   |
 |  58  | [Length of Last Word](https://leetcode.com/problems/length-of-last-word)                                                                                  |                                 [![Java](assets/java.png)](src/LengthOfLastWord.java) [![Python](assets/python.png)](python/length_of_last_word.py)                                  |                                                                                                                                   |
diff --git a/src/RotateImage.java b/src/RotateImage.java
@@ -0,0 +1,53 @@
+// https://leetcode.com/problems/rotate-image
+// T: O(n ^ 2)
+// S: O(1)
+
+public class RotateImage {
+    private static final class Point {
+        private final int row;
+        private final int column;
+
+        private Point(int row, int column) {
+            this.row = row;
+            this.column = column;
+        }
+    }
+
+    public void rotate(int[][] matrix) {
+        final int frames = (matrix.length + 1) / 2;
+        for (int frame = 0 ; frame < frames ; frame++) {
+            rotate90Degrees(matrix, frame);
+        }
+    }
+
+    private void rotate90Degrees(int[][] matrix, int frame) {
+        for (int i = 0 ; i < matrix.length - 2 * frame - 1 ; i++) {
+            Point p1 = getCoordinates(frame, 0, matrix.length, i);
+            int temp1 = get(matrix, p1), temp2;
+            for (int k = 0 ; k < 4 ; k++) {
+                Point p2 = getCoordinates(frame, (k + 1) % 4, matrix.length, i);
+                temp2 = get(matrix, p2);
+                set(matrix, p2, temp1);
+                temp1 = temp2;
+            }
+        }
+    }
+
+    private int get(int[][] matrix, Point point) {
+        return matrix[point.row][point.column];
+    }
+
+    private void set(int[][] matrix, Point point, int value) {
+        matrix[point.row][point.column] = value;
+    }
+
+    private Point getCoordinates(int frame, int k, int size, int shift) {
+        return switch (k) {
+            case 0 -> new Point(frame, frame + shift);
+            case 1 -> new Point(frame + shift, size - 1 - frame);
+            case 2 -> new Point(size - 1 - frame, size - 1 - frame - shift);
+            case 3 -> new Point(size - 1 - frame - shift, frame);
+            default -> null;
+        };
+    }
+}
