projecteuler---->problem=28----Number spiral diagonals

標籤：projecteuler   python   

Problem 28

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?

import timebegin = time.time()n = 1001num = n*nresu = 0count = n-1while num != 1:resu += 4*num-6*countnum = num - 4*countcount -= 2print resu+1end = time.time()print end-begin