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leetcode - Gas Station

2013-11-23 23:30  张汉生  阅读(161)  评论(0)    收藏  举报

 

 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 };