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