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gas stations

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.

 

public int canCompleteCircuit(int[] gas, int[] cost) {        if (gas == null) {            return -1;        }        // Note: The Solution object is instantiated only once and is reused by each test case.        int count = gas.length;                int n = 0;        int gasInCar = 0;        int begin = 0;        int end = 0;        int i = 0;        while (n < count - 1) {            gasInCar += gas[i] - cost[i];            if (gasInCar >=0) {//forward                end++;                i=end;            } else {                begin--;                if (begin < 0) {                    begin = count - 1;                }                i = begin;            }                        n++;        }                gasInCar += gas[i] - cost[i];                if (gasInCar >= 0) {            return begin;        } else {            return -1;        }            }

 

gas stations