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?
public class Solution { public void rotate(int[][] matrix) { int n = matrix.length; for(int i = 0 ; i < n/2 ; i++){ for(int j = i ; j < n-1-i ;j++){ int t = matrix[i][j]; matrix[i][j] = matrix[n-1-j][i]; matrix[n-1-j][i] = matrix[n-1-i][n-1-j]; matrix[n-1-i][n-1-j] = matrix[j][n-1-i]; matrix[j][n-1-i] = t; } } } }
learned: when switch from left up corner to right up corner ,switch i j position [0][0(j)] = [0(j)][4]