[Leetcode] Gas Station

最新推荐文章于 2019-10-23 11:28:34 发布

最新推荐文章于 2019-10-23 11:28:34 发布 · 231 阅读

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本文介绍了一个算法，用于解决环形油站路线问题。给定一系列油站和油箱容量限制，该算法确定从哪个油站出发可以完成环形路线，确保油箱在行驶过程中不会空油。

Gas Station

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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.

similar with max range sum.

class Solution {
public:
    int canCompleteCircuit(vector<int> &gas, vector<int> &cost) {
        int n = gas.size();
        vector<int> v(n);
        for (int i = 0; i < n; i++) v[i] = gas[i] - cost[i];
        int s = 0, e = 0, t = 0;
        while (s < n) {
            while (t >= 0 && e < s + n) t += v[(e++) % n];
            if (t >= 0 && e == s + n) return s;
            t -= v[s];
            s++;
        }
        return -1;
    }
};