[LeetCode 题解]:Gas Station
前言
【LeetCode 题解】系列传送门: http://www.cnblogs.com/double-win/category/573499.html
1.题目描述
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.
2. 思路
题解: 与经典的最大字段和问题类似,采用贪心策略。
3. 解法
1 class Solution { 2 public: 3 int canCompleteCircuit(vector<int> &gas, vector<int> &cost) { 4 int station = gas.size(); 5 int i,sum=0,start=0,total=0; 6 7 for(i=0;i<station;i++) 8 gas[i]-=cost[i]; 9 10 for(i=0;i<station;i++) total+=gas[i]; 11 if(total<0) return -1; 12 13 // 与求最大子段和类似,使用贪心策略 14 for(i=0;i<station;i++) 15 { 16 sum+= gas[i]; 17 if(sum<0) 18 { 19 start=i+1; // 如果当前和为负数,选择下一个元素作为起点 20 sum=0; 21 } 22 } 23 return start; 24 } 25 };
4. 相关题目
Maximum Subarray : http://www.cnblogs.com/double-win/p/3746672.html
作者:Double_Win 出处: http://www.cnblogs.com/double-win/p/3746637.html 声明: 由于本人水平有限,文章在表述和代码方面如有不妥之处,欢迎批评指正~ |