problem_18.py

import pprint
pp = pprint.PrettyPrinter(indent=4)

triangle = [
[75],
[95,64],
[17,47,82],
[18,35,87,10],
[20, 4,82,47,65],
[19, 1,23,75, 3,34],
[88, 2,77,73, 7,63,67],
[99,65, 4,28, 6,16,70,92],
[41,41,26,56,83,40,80,70,33],
[41,48,72,33,47,32,37,16,94,29],
[53,71,44,65,25,43,91,52,97,51,14],
[70,11,33,28,77,73,17,78,39,68,17,57],
[91,71,52,38,17,14,91,43,58,50,27,29,48],
[63,66, 4,68,89,53,67,30,73,16,69,87,40,31],
[ 4,62,98,27,23, 9,70,98,73,93,38,53,60, 4,23],
]

maxsum = 0
	
# starting from the row before the last of the triangle
# I update the current row with the max sum of the two possible values in the bottom row
# when i reach the top, I update the value "maxsum", that will be the solution

for x in reversed(range(len(triangle)-1)):
	curr_row = triangle[x]
	
	for i in range(len(curr_row)):
		try:
			sum1 = triangle[x][i] + triangle[x+1][i]
			sum2 = triangle[x][i] + triangle[x+1][i+1]
			triangle[x][i] = max(sum1,sum2)
		except IndexError:
			pass
	if x == 0:
		maxsum = triangle[x][0]

print("Solution is: "+str(maxsum))