navigation.py

# -*- coding: utf-8 -*-


def get_next_direction(direction):
    if direction == 'North':
        return 'East'
    if direction == 'East':
        return 'South'
    if direction == 'South':
        return 'West'
    if direction == 'West':
        return 'North'
    return 'North'


def solution(A):
    co_ordinates = []
    co_ordinate = [0, 0]
    direction = 'North'
    for index, steps in enumerate(A):
        for _ in xrange(0, steps):
            co_ordinates.append(co_ordinate[:])
            if direction == 'North':
                co_ordinate[1] += 1
            if direction == 'East':
                co_ordinate[0] += 1
            if direction == 'West':
                co_ordinate[0] -= 1
            if direction == 'South':
                co_ordinate[1] -= 1
            if co_ordinate in co_ordinates:
                return index + 1
        direction = get_next_direction(direction)
    return 0

print solution([
    1,
    3,
    2,
    5,
    4,
    4,
    6,
    3,
    2,
])
print solution([
    2,
    2,
    1,
    1,
    2,
    2,
    1,
    1,
])