[LeetCode]Gas Station

class Solution {public:    int canCompleteCircuit(vector<int> &gas, vector<int> &cost) {        // Note: The Solution object is instantiated only once and is reused by each test case.        int n = gas.size();        int curSum = 0;        int total = 0;        int pos = 0;        for(int i = 0; i < n; ++i)        {            int curRemain = gas[i]-cost[i];            if(curSum >= 0) curSum += curRemain;            else  curSum = curRemain, pos = i;            total += curRemain;        }        return total >= 0 ? pos: -1;    }};