48. Rotate image

One 、 Title Description

Given a n × n Two dimensional matrix of matrix Represents an image . Please rotate the image clockwise 90 degree .

You must be there. In situ Rotated image , This means that you need to modify the input two-dimensional matrix directly . Please do not Use another matrix to rotate the image .

Example 1：

 Input ：matrix = [[1,2,3],[4,5,6],[7,8,9]]
 Output ：[[7,4,1],[8,5,2],[9,6,3]]

Example 2：

 Input ：matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
 Output ：[[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]

Two 、 Problem solving

Flip instead of rotate

class Solution {
    
    public void rotate(int[][] matrix) {
    
        // This problem is to find rules 
        // First flip the array horizontally  , Then flip it according to the main diagonal 
        int n = matrix.length;
        if(matrix == null){
    
            return ;
        }
        // First flip according to the horizontal line 
        for(int i = 0;i<n/2;i++){
    
            for(int j = 0;j<n;j++){
    
                int temp = matrix[i][j];
                matrix[i][j] = matrix[n-i-1][j];
                matrix[n-i-1][j] = temp;
            }
        }

        // Flip in accordance with the main diagonal 
        for(int i = 0;i<n;i++){
    
            for(int j = 0;j<i;j++){
    
                int temp = matrix[i][j];
                matrix[i][j] = matrix[j][i];
                matrix[j][i] = temp;
            }
        }
    }
}