LeetCode: Gas Station

LeetCode: Gas Station 

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/**
 * Created by hzhou on 5/12/15. [email protected]
 */
public class GasStation {
    public int canCompleteCircuit(int[] gas, int[] cost) {
        if (gas == null || cost == null || gas.length != cost.length) {
            return -1;
        }
        int total, start, sumRemain;
        start = total = sumRemain = 0;
        for (int i = 0; i < gas.length; i++) {
            int remain = gas[i] - cost[i];
            if (sumRemain >= 0) {
                sumRemain += remain;
            } else {
                sumRemain = remain;
                start = i;
            }
            total += remain;
        }
        return total >= 0 ? start : -1;
    }
}