// Package q1137 implements a solution for https://leetcode.com/problems/n-th-tribonacci-number/
package q1137

func tribonacci(n int) int {
	a := [3]int{0, 1, 1}
	if n < 3 {
		return a[n]
	}
	for range n - 3 + 1 {
		a = [3]int{a[1], a[2], a[0] + a[1] + a[2]}
	}
	return a[2]
}

var _ = tribonacci