48. Rotate Image

You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

Follow up:
Could you do this in-place?

class Solution {
    public void rotate(int[][] matrix) {
        int N = matrix.length;
        // 先对矩阵转置
        for(int y = 0; y < N; y ++)
        {
            for(int x = y; x < N; x++)
            {
                int t = matrix[y][x];
                matrix[y][x] = matrix[x][y];
                matrix[x][y] = t;
            }
        }
        // 然后做一次左右对称
        for(int y = 0; y < N; y ++)
        {
            for(int x = 0; x < N/2; x++)
            {
                int t = matrix[y][x];
                matrix[y][x] = matrix[y][N-1-x];
                matrix[y][N-1-x] = t;
            }
        }
    }
}

class Solution {
    public void rotate(int[][] matrix) {
        int Len = matrix.length;
        for(int i=0; i<Len/2; i++){
            for (int j=i; j<Len-i-1; j++){
                rotating(matrix,i,j, Len);
            }
        }
    }
    
    public void rotating(int[][]matrix, int i,int j, int Len){
        int temp;
        temp=matrix[i][j];
        matrix[i][j]=matrix[Len-1-j][i];
        matrix[Len-1-j][i]=matrix[Len-1-i][Len-1-j];
        matrix[Len-1-i][Len-1-j]=matrix[j][Len-1-i];
        matrix[j][Len-1-i]=temp;
    }
}