package Leetcode.MathGeometry;

/**
 * @author zhengstars
 * @date 2024/06/03
 */
public class RotateImage {
    /**
     * Rotates the given n x n 2D matrix by 90 degrees clockwise.
     * The transformation is performed in-place without allocating additional space for another matrix.
     *
     * @param matrix The n x n 2D matrix to be rotated.
     */
    public static void rotate(int[][] matrix) {
        int n = matrix.length;

        // Step 1: Transpose the matrix
        // Transpose the matrix by swapping matrix[i][j] with matrix[j][i]
        // This changes rows into columns.
        // For example, the matrix:
        // 1 2 3
        // 4 5 6
        // 7 8 9
        // Will become:
        // 1 4 7
        // 2 5 8
        // 3 6 9
        for (int i = 0; i < n; i++) {
            for (int j = i; j < n; j++) {
                int temp = matrix[i][j];
                matrix[i][j] = matrix[j][i];
                matrix[j][i] = temp;
            }
        }

        // Step 2: Reverse each row
        // Reverse each row by swapping the elements at the start with the elements at the end.
        // For example, the matrix:
        // 1 4 7
        // 2 5 8
        // 3 6 9
        // Will become:
        // 7 4 1
        // 8 5 2
        // 9 6 3
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n / 2; j++) {
                int temp = matrix[i][j];
                matrix[i][j] = matrix[i][n - 1 - j];
                matrix[i][n - 1 - j] = temp;
            }
        }
    }

    public static void main(String[] args) {
        int[][] matrix1 = {
                {1, 2, 3},
                {4, 5, 6},
                {7, 8, 9}
        };
        rotate(matrix1);
        printMatrix(matrix1); // Expected output: [[7,4,1],[8,5,2],[9,6,3]]

        int[][] matrix2 = {
                {5, 1, 9, 11},
                {2, 4, 8, 10},
                {13, 3, 6, 7},
                {15, 14, 12, 16}
        };
        rotate(matrix2);
        printMatrix(matrix2); // Expected output: [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]
    }

    private static void printMatrix(int[][] matrix) {
        for (int[] row : matrix) {
            for (int val : row) {
                System.out.print(val + " ");
            }
            System.out.println();
        }
    }
}