rotate matrix

# Python program to rotate a matrix 
  
# Function to rotate a matrix 
def rotateMatrix(mat): 
  
    if not len(mat): 
        return
      
    """ 
        top : starting row index 
        bottom : ending row index 
        left : starting column index 
        right : ending column index 
    """
  
    top = 0
    bottom = len(mat)-1
  
    left = 0
    right = len(mat[0])-1
  
    while left < right and top < bottom: 
  
        # Store the first element of next row, 
        # this element will replace first element of 
        # current row 
        prev = mat[top+1][left] 
  
        # Move elements of top row one step right 
        for i in range(left, right+1): 
            curr = mat[top][i] 
            mat[top][i] = prev 
            prev = curr 
  
        top += 1
  
        # Move elements of rightmost column one step downwards 
        for i in range(top, bottom+1): 
            curr = mat[i][right] 
            mat[i][right] = prev 
            prev = curr 
  
        right -= 1
  
        # Move elements of bottom row one step left 
        for i in range(right, left-1, -1): 
            curr = mat[bottom][i] 
            mat[bottom][i] = prev 
            prev = curr 
  
        bottom -= 1
  
        # Move elements of leftmost column one step upwards 
        for i in range(bottom, top-1, -1): 
            curr = mat[i][left] 
            mat[i][left] = prev 
            prev = curr 
  
        left += 1
  
    return mat 
  
# Utility Function 
def printMatrix(mat): 
    for row in mat: 
        print row 
  
  
matrix = rotateMatrix(matrix) 
# Print modified matrix 
printMatrix(matrix)