环形路上有n个加油站,第i个加油站的汽油量是gas[i].
你有一辆车,车的油箱能够无限装汽油。从加油站i走到下一个加油站(i+1)花费的油量是cost[i],你从一个加油站出发,刚开始的时候油箱里面没有汽油。
求从哪一个加油站出发能够在环形路上走一圈。返回加油站的下标,若是没有答案的话返回-1。
注意:
答案保证惟一。web
There are N gas stations along a circular route, where the amount of gas at station i is gas[i].
You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to its next station (i+1). You begin the journey with an empty tank at one of the gas stations.
Return the starting gas station’s index if you can travel around the circuit once, otherwise return -1.
Note:
The solution is guaranteed to be unique.svg
输入ui
[2, 3, 1], [3, 1, 2]spa
输出code
1xml
情景应用题,比较简单,直接看代码吧。token
class Solution { public: /** * * @param gas int整型vector * @param cost int整型vector * @return int整型 */ int canCompleteCircuit(vector<int>& gas, vector<int>& cost) { // write code here int numOfStations = gas.size(); for(int i = 0; i < numOfStations; i++){ int tank = 0; for(int j = 0; j < numOfStations; j++){ int k = (i + j) % numOfStations; tank += gas[k] - cost[k]; if(tank < 0) break; } if(tank >= 0) return i; } return -1; } };
运行时间: 3ms
占用内存: 480KB内存