leetcode之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.

Note:

The solution is guaranteed to be unique.

问题链接

cpp代码如下：

class Solution {
public:
int canCompleteCircuit(vector<int> &gas, vector<int> &cost) {
int s=gas.size();
int total=0,sum=0;
int ans=0;
for(int i=0;i<s;++i){
total+=gas[i]-cost[i];
sum+=gas[i]-cost[i];
if(sum<0){
sum=0;
ans=i+1;
}
}
if(total<0)return -1;
return ans;
}
};