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.

#include<iostream>
#include<vector>
using namespace std;

int canCompleteCircuit(vector<int> &gas, vector<int> &cost) {
	int GasFirstId = 0;
	int GasEndId   = 0;
	int GasNum     = gas.size();
	int TotalCost  = 0;
	int CurIidx    = 0;

	for (int num = 0; num < GasNum;++num){                   //站点计数
		TotalCost += gas[CurIidx] - cost[CurIidx];
		if (TotalCost>=0){
			++GasEndId;
			CurIidx =GasEndId;
		}
		else{
			GasFirstId = GasFirstId == 0 ? GasNum - 1 : GasFirstId - 1;
			CurIidx = GasFirstId;
		}
	}
	if (TotalCost >= 0)
		return GasFirstId;
	else
		return -1;
}

Gas Station

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原文地址：http://blog.csdn.net/li_chihang/article/details/43485235