Interview question, rotate elements in 2D array 90 degrees clockwise

rotate_array.py

n = 5
arr = []

# populate array
for i in range(0, n):
    arr.append([])
    for j in range(0, n):
        arr[i].append(j)
        
# print before
print "Before:"
for x in arr:
    print x
    
offset = -1

# rotate CW 90 degrees
for row in range(0, n):
    offset += 1
    for col in range(offset, n):
        temp = arr[offset][col]
        arr[offset][col] = arr[col][offset]
        arr[col][offset] = temp
        
# print after
print "After:"
for x in arr:
    print x