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