题目：

题解：

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