48_RotateImage.java

link: https://leetcode.com/problems/rotate-image/

class Solution {
    public void rotate(int[][] matrix) {
        int n=matrix.length;
        for(int layer=0; layer<n/2; layer++){
            int first=layer;
            int last=n-1-layer;
            for(int i=first; i<last; i++){
                int offset = i-first;
                int top = matrix[layer][i];
                
                //left -> top
                matrix[layer][i] = matrix[last-offset][first];
                
                //bottom -> left
                matrix[last-offset][first] = matrix[last][last-offset];
                
                //right -> bottom
                matrix[last][last-offset] = matrix[i][last];
                
                //top -> right
                matrix[i][last] = top;
            }
        }
        
    }
}