package com.interview.leetcode.application;
/**
* Created_By: stefanie
* Date: 14-11-26
* Time: 下午10:43
*
* 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 class GasStation {
public int canCompleteCircuit(int[] gas, int[] cost) {
if(gas.length == 0 || cost.length == 0) return -1;
int total = 0;
int current = 0;
int start = 0;
for(int i = 0; i < gas.length; i++){
total += gas[i] - cost[i];
current += gas[i] - cost[i];
if(current < 0) {
current = 0;
start = i + 1;
}
}
return total >= 0? start : -1;
}
}