Gas Station

class Solution {public:    int canCompleteCircuit(vector<int> &gas, vector<int> &cost) {        const size_t size=gas.size();int curGas=0,total=0,record=0;for(size_t i=0;i<size;i++){curGas=curGas+gas[i]-cost[i];total=total+gas[i]-cost[i];if(curGas < 0){curGas=0;record=i+1;}}        return total>=0?record:-1;    }};