Class GasStations

java/Greedy/GasStations.java:3–26

import java.util.Arrays;

public class GasStations {
    public int gasStations(int[] gas, int[] cost) {
        // If the total gas is less than the total cost, completing the
        // circuit is impossible.
        if (Arrays.stream(gas).sum() < Arrays.stream(cost).sum()) {
            return -1;
        }
        int start, tank;
        start = tank = 0;
        for (int i = 0; i < gas.length; i++) {
            tank += gas[i] - cost[i];
            // If our tank has negative gas, we cannot continue through the 
            // circuit from the current start point, nor from any station 
            // before or including the current station 'i'.
            if (tank < 0) {
                // Set the next station as the new start point and reset the 
                // tank.
                start = i + 1;
                tank = 0;
            }
        }
        return start;
    }
}