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| 1 | +// https://leetcode.com/problems/rotate-image |
| 2 | +// T: O(n ^ 2) |
| 3 | +// S: O(1) |
| 4 | + |
| 5 | +public class RotateImage { |
| 6 | + private static final class Point { |
| 7 | + private final int row; |
| 8 | + private final int column; |
| 9 | + |
| 10 | + private Point(int row, int column) { |
| 11 | + this.row = row; |
| 12 | + this.column = column; |
| 13 | + } |
| 14 | + } |
| 15 | + |
| 16 | + public void rotate(int[][] matrix) { |
| 17 | + final int frames = (matrix.length + 1) / 2; |
| 18 | + for (int frame = 0 ; frame < frames ; frame++) { |
| 19 | + rotate90Degrees(matrix, frame); |
| 20 | + } |
| 21 | + } |
| 22 | + |
| 23 | + private void rotate90Degrees(int[][] matrix, int frame) { |
| 24 | + for (int i = 0 ; i < matrix.length - 2 * frame - 1 ; i++) { |
| 25 | + Point p1 = getCoordinates(frame, 0, matrix.length, i); |
| 26 | + int temp1 = get(matrix, p1), temp2; |
| 27 | + for (int k = 0 ; k < 4 ; k++) { |
| 28 | + Point p2 = getCoordinates(frame, (k + 1) % 4, matrix.length, i); |
| 29 | + temp2 = get(matrix, p2); |
| 30 | + set(matrix, p2, temp1); |
| 31 | + temp1 = temp2; |
| 32 | + } |
| 33 | + } |
| 34 | + } |
| 35 | + |
| 36 | + private int get(int[][] matrix, Point point) { |
| 37 | + return matrix[point.row][point.column]; |
| 38 | + } |
| 39 | + |
| 40 | + private void set(int[][] matrix, Point point, int value) { |
| 41 | + matrix[point.row][point.column] = value; |
| 42 | + } |
| 43 | + |
| 44 | + private Point getCoordinates(int frame, int k, int size, int shift) { |
| 45 | + return switch (k) { |
| 46 | + case 0 -> new Point(frame, frame + shift); |
| 47 | + case 1 -> new Point(frame + shift, size - 1 - frame); |
| 48 | + case 2 -> new Point(size - 1 - frame, size - 1 - frame - shift); |
| 49 | + case 3 -> new Point(size - 1 - frame - shift, frame); |
| 50 | + default -> null; |
| 51 | + }; |
| 52 | + } |
| 53 | +} |
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