package q134

func canCompleteCircuit(gas []int, cost []int) int {
	invalidated := 0
	start, current, tank := 0, 0, 0

	for {
		tank = tank + gas[current] - cost[current]
		current = (current + 1) % len(gas)
		if tank < 0 {
			invalidated += (current - start + len(gas)) % len(gas)
			if invalidated >= len(gas) || current == start {
				return -1
			}
			start = current
			tank = 0
		} else if current == start {
			return start
		}
	}
}

var _ = canCompleteCircuit