Gas Station
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.
读懂题意就好
后面的验证没必要
class Solution { public: int canCompleteCircuit(vector<int> &gas, vector<int> &cost) { if(gas.size()!= cost.size())return -1; int size = gas.size(); if(size == 0) return -1; vector<int> left(size,0); int sum = 0 ; int min = 0 ; int min_sum =sum; for(int i = 0 ; i < size ;i++) { left[i] = gas[i] - cost[i]; sum += left[i]; if(sum < min_sum){ min = i; min_sum = sum; } } if(sum < 0)return -1; sum = 0; int index = (min+1)%size; for(int i = 0 ; i < size ;i++) { sum += left[index]; index = (index+1)%size; if(sum<0)return -1; } return (min+1)%size; } };
posted on 2014-03-31 16:18 pengyu2003 阅读(213) 评论(0) 编辑 收藏 举报