Rotate a Square Image Counterclockwise

Image Rotation can be simplified if you can break up the process into smaller sub-problems. Rotating a matrix counterclockwise is the same as first taking the transpose of the matrix and then flipping it along its horizontal axis!

Remember this pattern for all 2D array problems : int rows = matrix.length and int columns = matrix[0].length. In your learning program you may have come across the following sub-problems - Find the transpose of a square matrix and Flip an image on its horizontal axis. If we combine the two - we're done! transposeMatrix + flipItHorizontalAxis. As a refresher, here's the pattern for getting the transpose of a matrix :

for(int i = 0; i <= n; i++){
 for(int j = i+1; j <= n; j++){
  int temp = matrix[i][j];
  matrix[i][j] = matrix[j][i];
  matrix[j][i] = temp;
 }
}