cc 1.6

rotationMatrix.py

#cc 1.6 Given an image represented by an N*N matrix, where each pixel in the image is 4 bytes. write a method to rotate the image by 90 degrees
#Assume clockwise rotation

def rotate(matrix):

    n = len(matrix)
    for layer in range(0, n/2):
        first = layer
        last = n-layer-1
        for i in range(first, last):
            offset = i - first
            '''save the top'''
            top = matrix[first][i]
            '''left to top'''
            matrix[first][i] = matrix[last - offset][first]
            '''bottom to left'''
            matrix[last - offset] [first] = matrix[last][last - offset]
            '''right to bottom'''
            matrix[last][last - offset] = matrix[i][last]
            '''top to right'''
            matrix[i][last] = top

    return matrix
#test case
matrix = ([1,2,3,6,7], [4,5,6,9,10], [7,8,9,5,6], [5,7,8,3,2], [8,6,5,0,7])
print 'the original matrix:', matrix
print 'After rotation:', rotate(matrix)