package q1411

type Color uint8

const MODULO int = 1e9 + 7

func numOfWays(n int) int {
	patterns := make([][3]Color, 0, 12)
	for a := range 3 {
		for b := range 3 {
			for c := range 3 {
				if a == b || b == c {
					continue
				}
				patterns = append(patterns, [3]Color{Color(a), Color(b), Color(c)})
			}
		}
	}

	// Find compatible patterns
	compatiblePtns := make([][]int, len(patterns))
	for i := range len(patterns) - 1 {
		for j := i + 1; j < len(patterns); j++ {
			ok := true
			for k := range 3 {
				if patterns[i][k] == patterns[j][k] {
					ok = false
					break
				}
			}
			if ok {
				compatiblePtns[i] = append(compatiblePtns[i], j)
				compatiblePtns[j] = append(compatiblePtns[j], i)
			}
		}
	}

	counts := make([]int, len(patterns))
	for i := range counts {
		counts[i] = 1
	}

	countsNext := make([]int, len(patterns))
	for range n - 1 {
		for i := range len(patterns) {
			countsNext[i] = 0
			for _, j := range compatiblePtns[i] {
				countsNext[i] += counts[j]
			}
			countsNext[i] %= MODULO
		}
		counts, countsNext = countsNext, counts
	}

	sum := 0
	for _, c := range counts {
		sum += c
	}
	return sum % MODULO
}

var _ = numOfWays