1 class Solution {
2 public:
3 int canCompleteCircuit(vector<int> &gas, vector<int> &cost) {
4 // IMPORTANT: Please reset any member data you declared, as
5 // the same Solution instance will be reused for each test case.
6 if (gas.size()<=0)
7 return -1;
8 if (gas.size()==1){
9 if (gas[0]>=cost[0])
10 return 0;
11 else return -1;
12 }
13 int n = gas.size();
14 int remainChecks = n;
15 int curSum = 0;
16 for (int i=0; i<n; i++){
17 int index = -1;
18 //cout << "start check: i= " << i << ",remain="<<remainChecks << ",curSum=" << curSum << endl;
19 while (remainChecks>0 && curSum>=0){
20 index = (i+(n-remainChecks))%n;
21 curSum += gas[index] - cost[index];
22 remainChecks--;
23 }
24 if (remainChecks==0 && curSum>=0)
25 return i;
26 curSum -= gas[i] - cost[i];
27 remainChecks++;
28 }
29 return -1;
30 }
31 };
