Gas station completing the circuit

gas_station_complete_circle.py

"""
https://scammingthecodinginterview.com
Week 3: Greedy
Problem: 2
"""


class Solution(object):

    def solve(self, fuel, cost):

        n = len(fuel)
        end = 0
        start = n - 1

        sum = fuel[start] - cost[start]

        while start > end:

            if sum >= 0:
                sum = sum + fuel[end] - cost[end]
                end+=1
            else:
                start -= 1
                sum += fuel[start] - cost[start]

        return start if sum >= 0 else -1


if __name__ == "__main__":

    fuel = [1, 2, 3, 4, 5]
    cost = [3, 4, 5, 1, 2]

    ans = Solution().solve(fuel, cost)

    print(ans)