https://leetcode.com/problems/rotate-image/submissions/

rotate-image.java

class Solution {
    public void rotate(int[][] matrix) {
        trans(matrix);
        flip(matrix);
    }
    
    private void trans(int[][] matrix) {
        int row = matrix.length;
        int col = matrix[0].length;
        for (int i = 0; i < row; i++) {
            for (int j = i + 1; j < col; j++) {
                int tmp = matrix[i][j];
                matrix[i][j] = matrix[j][i];
                matrix[j][i] = tmp;
            }
        }
    }
    
    private void flip(int[][] matrix) {
        int row = matrix.length;
        int col = matrix[0].length;
        for (int i = 0; i < row; i++) {
            for (int j = 0; j < col / 2; j++) {
                int tmp = matrix[i][j];
                matrix[i][j] = matrix[i][ col - 1 - j];
                matrix[i][col - 1 - j] = tmp;
            }
        }
    }
    
}