# leetcode 134. 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.

class Solution {
public:
int canCompleteCircuit(vector<int>& gas, vector<int>& cost) {
int start = gas.size() - 1;
int end = 0;
int sum = 0;
sum = gas[start] - cost[start];
while(start > end) {
if(sum >= 0) {
sum += gas[end] - cost[end];
end++;

}
else {
start--;
sum += gas[start] - cost[start];
}
}
return sum >= 0 ? start : -1;

}
};


10 May 2017 2:19 PM