#134

Gas Station

medium· Greedyruns: 0

There are n gas stations along a circular route, where the amount of gas at the ith station is gas[i]. You have a car with an unlimited tank, and it costs cost[i] of gas to travel from the ith station to the next. You begin the journey with an empty tank at one of the gas stations. Given two integer arrays gas and cost, return the starting station's index if you can travel around the circuit once in the clockwise direction, otherwise return -1. The solution, if it exists, is unique.

wpm 0acc 100%time 0:000 / 366

class Solution:
    def canCompleteCircuit(
        self, gas: list[int], cost: list[int]
    ) -> int:
        if sum(gas) < sum(cost):
            return -1
        start = 0
        tank = 0
        for i in range(len(gas)):
            tank += gas[i] - cost[i]
            if tank < 0:
                start = i + 1
                tank = 0
        return start

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