LeetCode – Refresh – Gas Station

 1 class Solution {
 2 public:
 3     int canCompleteCircuit(vector<int> &gas, vector<int> &cost) {
 4         int len = gas.size(), total = 0, sum = 0, index = 0;
 5         if (len == 0 || len != cost.size()) return -1;
 6         for (int i = 0; i < len; i++) {
 7             total += gas[i] - cost[i];
 8             sum += gas[i] - cost[i];
 9             if (sum < 0) {
10                 sum = 0;
11                 index = i + 1;
12             }
13         }
14         return total < 0 ? -1 : index;
15     }
16 };