euler/e028.py

"""What is the sum of both diagonals in a 1001 by 1001 spiral?

Starting with the number 1 and moving to the right in a clockwise direction a 5 by 5 spiral is formed as follows:

   [21]22 23 24[25]
    20 [7] 8 [9]10
    19  6 [1] 2 11
    18 [5] 4 [3]12
   [17]16 15 14[13]

It can be verified that the sum of the numbers on the diagonals is 101.
What is the sum of the numbers on the diagonals in a 1001 by 1001 spiral formed in the same way?
"""

def main():
    n = 1
    total = 1
    size = 1
    
    MAX_SIZE = 1001
    
    while size <= MAX_SIZE:
        for i in range(4):
            n = n + (size - 1)
            if n > 1:
                total = total + n
        size = size + 2
    
    print 'Total:', total

if __name__ == '__main__':
    main()