class Solution {
    public void rotate(int[][] matrix) {
        int layer = 0;
        int n = matrix.length;
        int value = 0;
        int[] values = new int[n];

        while (layer < n/2) {
            for (int i=layer; i<n-1-layer; i++) { //top to right
                values[i] = matrix[i][n-1-layer];
                matrix[i][n-1-layer] = matrix[layer][i];
            }
            for (int i=layer; i<n-1-layer; i++) {//right to bottom
                value = values[i];
                values[i] = matrix[n-1-layer][n-1-i];
                matrix[n-1-layer][n-1-i] = value;
            }
            for (int i=layer; i<n-1-layer; i++) {//bottom to left
                value = values[i];
                values[i] = matrix[n-1-i][layer];
                matrix[n-1-i][layer] = value;
            }
            for (int i=layer; i<n-1-layer; i++) {//left to top
                value = values[i];
                matrix[layer][i] = value;
            }

            layer++;
        }
    }
}