There are N gas stations along a circular route, where the amount of gas at station i is gas[i].

You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to its next station (i+1). You begin the journey with an empty tank at one of the gas stations.

Return the starting gas station's index if you can travel around the circuit once, otherwise return -1.

Note:

The solution is guaranteed to be unique.

超时代码O(n²)：

class Solution{  public:      int canCompleteCircuit(vector
     
       &gas, vector
      
        &cost) {          if(gas.empty()||cost.empty()) return -1;          int myToalGas=0;          int remain=0;          for (int i=0;i
       
        =0) continue;                  else break;              }              if(j==gas.size()) return i;          }          return -1;      }  };