You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).
You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.
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]]
Example 3:
Input: matrix = [[1]]
Output: [[1]]
Example 4:
Input: matrix = [[1,2],[3,4]]
Output: [[3,1],[4,2]]
Constraints:
matrix.length == n
matrix[i].length == n
1 <= n <= 20
-1000 <= matrix[i][j] <= 1000
public class Solution {
public void Rotate(int[][] matrix) {
if(matrix.Length==0){
return;
}
int s = 0;
int e = matrix.Length-1;
while(s < e){
var temp = matrix[s];
matrix[s]=matrix[e];
matrix[e]=temp;
s++;
e--;
}
for(int i=0; i< matrix.Length;i++){
for(int j=i+1;j<matrix.Length;j++){
int temp = matrix[i][j];
matrix[i][j]=matrix[j][i];
matrix[j][i]=temp;
}
}
}
}
Time Complexity: O(m*n)
Space Complexity: O(1)
Where m and n are rows and columns of matrix.