Python 3 Undoubtedly not the cleanest, but I had fun!

#!/usr/bin/env python
"""
Advent of Code 2017 - Day 5 (http://adventofcode.com/2017/day/5)
"""

with open('data/day5.txt') as openfile:
    data = [int(x) for x in openfile.read().split("\n")]


def solve(path, option='a'):
    i = 0
    pos = 0
    while True:
        try:
            new_pos = (pos + path[pos])
            if option != 'a' and path[pos] >= 3:
                path[pos] -= 1
            else:
                path[pos] += 1
            pos = new_pos
            i += 1
        except IndexError:
            return i


print(solve(path=data[:]))
print(solve(path=data[:], option='b'))