ProjectEuler#18#67 Maximum path sum I and II

#By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total #from top to bottom is 23.

#3
#7 4
#2 4 6
#8 5 9 3

#That is, 3 + 7 + 4 + 9 = 23.

#Find the maximum total from top to bottom of the triangle below:

#75
#95 64
#17 47 82
#18 35 87 10
#20 04 82 47 65
#19 01 23 75 03 34
#88 02 77 73 07 63 67
#99 65 04 28 06 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 04 68 89 53 67 30 73 16 69 87 40 31
#04 62 98 27 23 09 70 98 73 93 38 53 60 04 23

#NOTE: As there are only 16384 routes, it is possible to solve this problem by trying every route. However, Problem #67, is the same challenge with a triangle containing one-hundred rows; it cannot be solved by brute force, and #requires a clever method! ;o)

#Analysis
#starting the search from the bottom to the top, adding the maximums along the way. This will “bubble” the maximum #total to the top of the pyramid

arr = [[int(i) for i in line.split()] for line in open('input.txt')]

for i in range(len(arr)-1,0,-1):
    for j in range(len(arr[i])-1):
        if arr[i][j] >= arr[i][j+1]:
            arr[i-1][j] += arr[i][j]
        else:
            arr[i-1][j] += arr[i][j+1]
print arr[0][0]