48. Rotate Image

[yikaikai]

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

Rotate the image by 90 degrees (clockwise).

Note:

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:

Given input matrix =
[
[1,2,3],
[4,5,6],
[7,8,9]
],

rotate the input matrix in-place such that it becomes:
[
[7,4,1],
[8,5,2],
[9,6,3]
]
Example 2:

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

rotate the input matrix in-place such that it becomes:
[
[15,13, 2, 5],
[14, 3, 4, 1],
[12, 6, 8, 9],
[16, 7,10,11]
]

 void rotate(vector<vector<int>>& matrix) {

int width = matrix[0].size();

    for (int row = 0; row <= (width - 1) / 2; row++) {
        for (int col = row; col < width - 1 - row; col++) {
            int tmp = matrix[row][col];

            matrix[row][col] = matrix[width - 1 - col][row];
            matrix[width - 1 - col][row] = matrix[width - 1 - row][width - 1 - col];
            matrix[width - 1 - row][width - 1 - col] = matrix[col][width - 1 - row];
            matrix[col][width - 1 - row] = tmp;
        }
    }
 }