gastation.cpp

//leetcode Gas Station 134 Medium challenge
//https://leetcode.com/problems/gas-station/

#include <vector>

using namespace std;

class Solution
{
public:
    int canCompleteCircuit(vector<int> &gas, vector<int> &cost)
    {
        int total_gas = 0, total_cost = 0, tank = 0, start = 0;

        for (int i = 0; i < gas.size(); i++)
        {
            total_gas += gas[i];
            total_cost += cost[i];
        }

        if (total_gas < total_cost)
            return -1;

        for (int i = 0; i < gas.size(); i++)
        {
            tank += gas[i] - cost[i];

            if (tank < 0)
            {
                start = i + 1;
                tank = 0;
            }
        }

        return start;
    }
};