new_contents: class Solution:
      # @param gas, a list of integers
      # @param cost, a list of integers
      # @return an integer
      def canCompleteCircuit(self, gas, cost):
          # write your code here
  
          # Solution 1
          total_left_gas = 0
          sum = 0
          res = 0
          for i in range(len(gas)):
              sum = sum + gas[i] - cost[i]
              if (sum < 0):
                  sum = 0
                  res = i + 1
              total_left_gas += gas[i] - cost[i]
          return -1 if total_left_gas < 0 or res >= len(gas) else res
  
subject: Add solution to lintcode question 187