134. Gas Station

1. 题目：https://leetcode.com/problems/gas-station/
2. 思路：遍历所有的可能，一旦不能走到最后直接break，一直有油则return i， 所有可能遍历完之后还没有解答就return -1
3. 坑：一遍过的代码
4. 代码：

   class Solution {
   public:
       int canCompleteCircuit(vector& gas, vector& cost) {
           int cur_gas = 0;
           int gas_num = gas.size();
           for (int i = 0; i < gas.size(); i++) {
               cur_gas = gas[i];
               for (int j = 0; j < gas.size(); j++) {
                   cur_gas -= cost[(i+j)%gas_num];
                   if (cur_gas < 0)
                       break;
                   cur_gas += gas[(i+j+1)%gas_num];
               }
               if (cur_gas >= 0)
                   return i;
           }
           return -1;
       }
   };