diff --git a/codes/codes.go b/codes/codes.go
index 5c349c7..6fbe5ac 100644
--- a/codes/codes.go
+++ b/codes/codes.go
@@ -1,271 +1,26 @@
 package codes
 
 type Code struct {
-	Value uint16
-	Bits  int
+	Value uint32
+	Bits  uint8
 }
 
-var codes = []Code{
-	{Value: 0b0000, Bits: 4},
-	{Value: 0b0001, Bits: 4},
-	{Value: 0b0010, Bits: 4},
-	{Value: 0b0011, Bits: 4},
-	{Value: 0b01000, Bits: 5},
-	{Value: 0b01001, Bits: 5},
-	{Value: 0b01010, Bits: 5},
-	{Value: 0b01011, Bits: 5},
-	{Value: 0b011000, Bits: 6},
-	{Value: 0b011001, Bits: 6},
-	{Value: 0b011010, Bits: 6},
-	{Value: 0b011011, Bits: 6},
-	{Value: 0b011100, Bits: 6},
-	{Value: 0b011101, Bits: 6},
-	{Value: 0b011110, Bits: 6},
-	{Value: 0b011111, Bits: 6},
-	{Value: 0b1000000, Bits: 7},
-	{Value: 0b1000001, Bits: 7},
-	{Value: 0b1000010, Bits: 7},
-	{Value: 0b1000011, Bits: 7},
-	{Value: 0b1000100, Bits: 7},
-	{Value: 0b1000101, Bits: 7},
-	{Value: 0b1000110, Bits: 7},
-	{Value: 0b1000111, Bits: 7},
-	{Value: 0b1001000, Bits: 7},
-	{Value: 0b1001001, Bits: 7},
-	{Value: 0b1001010, Bits: 7},
-	{Value: 0b1001011, Bits: 7},
-	{Value: 0b1001100, Bits: 7},
-	{Value: 0b1001101, Bits: 7},
-	{Value: 0b1001110, Bits: 7},
-	{Value: 0b1001111, Bits: 7},
-	{Value: 0b10100000, Bits: 8},
-	{Value: 0b10100001, Bits: 8},
-	{Value: 0b10100010, Bits: 8},
-	{Value: 0b10100011, Bits: 8},
-	{Value: 0b10100100, Bits: 8},
-	{Value: 0b10100101, Bits: 8},
-	{Value: 0b10100110, Bits: 8},
-	{Value: 0b10100111, Bits: 8},
-	{Value: 0b10101000, Bits: 8},
-	{Value: 0b10101001, Bits: 8},
-	{Value: 0b10101010, Bits: 8},
-	{Value: 0b10101011, Bits: 8},
-	{Value: 0b10101100, Bits: 8},
-	{Value: 0b10101101, Bits: 8},
-	{Value: 0b10101110, Bits: 8},
-	{Value: 0b10101111, Bits: 8},
-	{Value: 0b10110000, Bits: 8},
-	{Value: 0b10110001, Bits: 8},
-	{Value: 0b10110010, Bits: 8},
-	{Value: 0b10110011, Bits: 8},
-	{Value: 0b10110100, Bits: 8},
-	{Value: 0b10110101, Bits: 8},
-	{Value: 0b10110110, Bits: 8},
-	{Value: 0b10110111, Bits: 8},
-	{Value: 0b10111000, Bits: 8},
-	{Value: 0b10111001, Bits: 8},
-	{Value: 0b10111010, Bits: 8},
-	{Value: 0b10111011, Bits: 8},
-	{Value: 0b10111100, Bits: 8},
-	{Value: 0b10111101, Bits: 8},
-	{Value: 0b10111110, Bits: 8},
-	{Value: 0b10111111, Bits: 8},
-	{Value: 0b110000000, Bits: 9},
-	{Value: 0b110000001, Bits: 9},
-	{Value: 0b110000010, Bits: 9},
-	{Value: 0b110000011, Bits: 9},
-	{Value: 0b110000100, Bits: 9},
-	{Value: 0b110000101, Bits: 9},
-	{Value: 0b110000110, Bits: 9},
-	{Value: 0b110000111, Bits: 9},
-	{Value: 0b110001000, Bits: 9},
-	{Value: 0b110001001, Bits: 9},
-	{Value: 0b110001010, Bits: 9},
-	{Value: 0b110001011, Bits: 9},
-	{Value: 0b110001100, Bits: 9},
-	{Value: 0b110001101, Bits: 9},
-	{Value: 0b110001110, Bits: 9},
-	{Value: 0b110001111, Bits: 9},
-	{Value: 0b110010000, Bits: 9},
-	{Value: 0b110010001, Bits: 9},
-	{Value: 0b110010010, Bits: 9},
-	{Value: 0b110010011, Bits: 9},
-	{Value: 0b110010100, Bits: 9},
-	{Value: 0b110010101, Bits: 9},
-	{Value: 0b110010110, Bits: 9},
-	{Value: 0b110010111, Bits: 9},
-	{Value: 0b110011000, Bits: 9},
-	{Value: 0b110011001, Bits: 9},
-	{Value: 0b110011010, Bits: 9},
-	{Value: 0b110011011, Bits: 9},
-	{Value: 0b110011100, Bits: 9},
-	{Value: 0b110011101, Bits: 9},
-	{Value: 0b110011110, Bits: 9},
-	{Value: 0b110011111, Bits: 9},
-	{Value: 0b110100000, Bits: 9},
-	{Value: 0b110100001, Bits: 9},
-	{Value: 0b110100010, Bits: 9},
-	{Value: 0b110100011, Bits: 9},
-	{Value: 0b110100100, Bits: 9},
-	{Value: 0b110100101, Bits: 9},
-	{Value: 0b110100110, Bits: 9},
-	{Value: 0b110100111, Bits: 9},
-	{Value: 0b110101000, Bits: 9},
-	{Value: 0b110101001, Bits: 9},
-	{Value: 0b110101010, Bits: 9},
-	{Value: 0b110101011, Bits: 9},
-	{Value: 0b110101100, Bits: 9},
-	{Value: 0b110101101, Bits: 9},
-	{Value: 0b110101110, Bits: 9},
-	{Value: 0b110101111, Bits: 9},
-	{Value: 0b110110000, Bits: 9},
-	{Value: 0b110110001, Bits: 9},
-	{Value: 0b110110010, Bits: 9},
-	{Value: 0b110110011, Bits: 9},
-	{Value: 0b110110100, Bits: 9},
-	{Value: 0b110110101, Bits: 9},
-	{Value: 0b110110110, Bits: 9},
-	{Value: 0b110110111, Bits: 9},
-	{Value: 0b110111000, Bits: 9},
-	{Value: 0b110111001, Bits: 9},
-	{Value: 0b110111010, Bits: 9},
-	{Value: 0b110111011, Bits: 9},
-	{Value: 0b110111100, Bits: 9},
-	{Value: 0b110111101, Bits: 9},
-	{Value: 0b110111110, Bits: 9},
-	{Value: 0b110111111, Bits: 9},
-	{Value: 0b1110000000, Bits: 10},
-	{Value: 0b1110000001, Bits: 10},
-	{Value: 0b1110000010, Bits: 10},
-	{Value: 0b1110000011, Bits: 10},
-	{Value: 0b1110000100, Bits: 10},
-	{Value: 0b1110000101, Bits: 10},
-	{Value: 0b1110000110, Bits: 10},
-	{Value: 0b1110000111, Bits: 10},
-	{Value: 0b1110001000, Bits: 10},
-	{Value: 0b1110001001, Bits: 10},
-	{Value: 0b1110001010, Bits: 10},
-	{Value: 0b1110001011, Bits: 10},
-	{Value: 0b1110001100, Bits: 10},
-	{Value: 0b1110001101, Bits: 10},
-	{Value: 0b1110001110, Bits: 10},
-	{Value: 0b1110001111, Bits: 10},
-	{Value: 0b1110010000, Bits: 10},
-	{Value: 0b1110010001, Bits: 10},
-	{Value: 0b1110010010, Bits: 10},
-	{Value: 0b1110010011, Bits: 10},
-	{Value: 0b1110010100, Bits: 10},
-	{Value: 0b1110010101, Bits: 10},
-	{Value: 0b1110010110, Bits: 10},
-	{Value: 0b1110010111, Bits: 10},
-	{Value: 0b1110011000, Bits: 10},
-	{Value: 0b1110011001, Bits: 10},
-	{Value: 0b1110011010, Bits: 10},
-	{Value: 0b1110011011, Bits: 10},
-	{Value: 0b1110011100, Bits: 10},
-	{Value: 0b1110011101, Bits: 10},
-	{Value: 0b1110011110, Bits: 10},
-	{Value: 0b1110011111, Bits: 10},
-	{Value: 0b1110100000, Bits: 10},
-	{Value: 0b1110100001, Bits: 10},
-	{Value: 0b1110100010, Bits: 10},
-	{Value: 0b1110100011, Bits: 10},
-	{Value: 0b1110100100, Bits: 10},
-	{Value: 0b1110100101, Bits: 10},
-	{Value: 0b1110100110, Bits: 10},
-	{Value: 0b1110100111, Bits: 10},
-	{Value: 0b1110101000, Bits: 10},
-	{Value: 0b1110101001, Bits: 10},
-	{Value: 0b1110101010, Bits: 10},
-	{Value: 0b1110101011, Bits: 10},
-	{Value: 0b1110101100, Bits: 10},
-	{Value: 0b1110101101, Bits: 10},
-	{Value: 0b1110101110, Bits: 10},
-	{Value: 0b1110101111, Bits: 10},
-	{Value: 0b1110110000, Bits: 10},
-	{Value: 0b1110110001, Bits: 10},
-	{Value: 0b1110110010, Bits: 10},
-	{Value: 0b1110110011, Bits: 10},
-	{Value: 0b1110110100, Bits: 10},
-	{Value: 0b1110110101, Bits: 10},
-	{Value: 0b1110110110, Bits: 10},
-	{Value: 0b1110110111, Bits: 10},
-	{Value: 0b1110111000, Bits: 10},
-	{Value: 0b1110111001, Bits: 10},
-	{Value: 0b1110111010, Bits: 10},
-	{Value: 0b1110111011, Bits: 10},
-	{Value: 0b1110111100, Bits: 10},
-	{Value: 0b1110111101, Bits: 10},
-	{Value: 0b1110111110, Bits: 10},
-	{Value: 0b1110111111, Bits: 10},
-	{Value: 0b1111000000, Bits: 10},
-	{Value: 0b1111000001, Bits: 10},
-	{Value: 0b1111000010, Bits: 10},
-	{Value: 0b1111000011, Bits: 10},
-	{Value: 0b1111000100, Bits: 10},
-	{Value: 0b1111000101, Bits: 10},
-	{Value: 0b1111000110, Bits: 10},
-	{Value: 0b1111000111, Bits: 10},
-	{Value: 0b1111001000, Bits: 10},
-	{Value: 0b1111001001, Bits: 10},
-	{Value: 0b1111001010, Bits: 10},
-	{Value: 0b1111001011, Bits: 10},
-	{Value: 0b1111001100, Bits: 10},
-	{Value: 0b1111001101, Bits: 10},
-	{Value: 0b1111001110, Bits: 10},
-	{Value: 0b1111001111, Bits: 10},
-	{Value: 0b1111010000, Bits: 10},
-	{Value: 0b1111010001, Bits: 10},
-	{Value: 0b1111010010, Bits: 10},
-	{Value: 0b1111010011, Bits: 10},
-	{Value: 0b1111010100, Bits: 10},
-	{Value: 0b1111010101, Bits: 10},
-	{Value: 0b1111010110, Bits: 10},
-	{Value: 0b1111010111, Bits: 10},
-	{Value: 0b1111011000, Bits: 10},
-	{Value: 0b1111011001, Bits: 10},
-	{Value: 0b1111011010, Bits: 10},
-	{Value: 0b1111011011, Bits: 10},
-	{Value: 0b1111011100, Bits: 10},
-	{Value: 0b1111011101, Bits: 10},
-	{Value: 0b1111011110, Bits: 10},
-	{Value: 0b1111011111, Bits: 10},
-	{Value: 0b1111100000, Bits: 10},
-	{Value: 0b1111100001, Bits: 10},
-	{Value: 0b1111100010, Bits: 10},
-	{Value: 0b1111100011, Bits: 10},
-	{Value: 0b1111100100, Bits: 10},
-	{Value: 0b1111100101, Bits: 10},
-	{Value: 0b1111100110, Bits: 10},
-	{Value: 0b1111100111, Bits: 10},
-	{Value: 0b1111101000, Bits: 10},
-	{Value: 0b1111101001, Bits: 10},
-	{Value: 0b1111101010, Bits: 10},
-	{Value: 0b1111101011, Bits: 10},
-	{Value: 0b1111101100, Bits: 10},
-	{Value: 0b1111101101, Bits: 10},
-	{Value: 0b1111101110, Bits: 10},
-	{Value: 0b1111101111, Bits: 10},
-	{Value: 0b1111110000, Bits: 10},
-	{Value: 0b1111110001, Bits: 10},
-	{Value: 0b1111110010, Bits: 10},
-	{Value: 0b1111110011, Bits: 10},
-	{Value: 0b1111110100, Bits: 10},
-	{Value: 0b1111110101, Bits: 10},
-	{Value: 0b1111110110, Bits: 10},
-	{Value: 0b1111110111, Bits: 10},
-	{Value: 0b1111111000, Bits: 10},
-	{Value: 0b1111111001, Bits: 10},
-	{Value: 0b1111111010, Bits: 10},
-	{Value: 0b1111111011, Bits: 10},
-	{Value: 0b1111111100, Bits: 10},
-	{Value: 0b1111111101, Bits: 10},
-	{Value: 0b11111111100, Bits: 11},
-	{Value: 0b11111111101, Bits: 11},
-	{Value: 0b11111111110, Bits: 11},
-	{Value: 0b11111111111, Bits: 11},
-}
+func CodeForIndex(index uint32) Code {
+	switch {
+	case index < 4:
+		return Code{Value: index, Bits: 4}
+	case index < 8:
+		return Code{Value: 0b01000 + (index & 0b00011), Bits: 5}
+	case index < 16:
+		return Code{Value: 0b011000 + (index & 0b000111), Bits: 6}
+	case index < 32:
+		return Code{Value: 0b1000000 + (index & 0b0001111), Bits: 7}
+	default:
+		set := uint8(index / uint32(64))
 
-func CodeForIndex(index int) Code {
-	return codes[index]
+		return Code{
+			Value: (((2 << set) - 1) << 7) + (index % uint32(64)),
+			Bits:  set + 8,
+		}
+	}
 }
diff --git a/encode.go b/encode.go
index c466c5e..cbde1ba 100644
--- a/encode.go
+++ b/encode.go
@@ -16,7 +16,7 @@ func Encode(st *state.State, msg []byte) []byte {
 	for i := 0; i < len(msg); {
 		l, index := st.IncrementSymbol(msg[i:])
 		i += l
-		code := codes.CodeForIndex(index)
+		code := codes.CodeForIndex(uint32(index))
 		lo.Must0(w.WriteBits(uint64(code.Value), uint8(code.Bits)))
 	}
 
diff --git a/gencodes/main.go b/gencodes/main.go
deleted file mode 100644
index eb1aa38..0000000
--- a/gencodes/main.go
+++ /dev/null
@@ -1,79 +0,0 @@
-package main
-
-import (
-	"log"
-	"strings"
-)
-
-func main() {
-	// Generate all possible values up to 10 bits
-	byLen := map[int][]string{
-		1: []string{"0", "1"},
-	}
-
-	for l := 2; l <= 10; l++ {
-		values := []string{}
-
-		for _, v := range byLen[l-1] {
-			values = append(values, v+"0", v+"1")
-		}
-
-		byLen[l] = values
-	}
-
-	limits := map[int]int{
-		1:  0,
-		2:  0,
-		3:  0,
-		4:  2,
-		5:  8,
-		6:  8,
-		7:  16,
-		8:  32,
-		9:  64,
-		10: 256,
-	}
-
-	total := 0
-	short := 0
-
-	for l := 1; l <= 10; l++ {
-		vs := byLen[l]
-		limit := limits[l]
-		values := []string{}
-
-	valueLoop:
-		for _, v := range vs {
-			if limit == 0 {
-				break
-			}
-
-			for i := 1; i < l; i++ {
-				for _, v2 := range byLen[i] {
-					if strings.HasPrefix(v, v2) {
-						continue valueLoop
-					}
-				}
-			}
-
-			values = append(values, v)
-			limit--
-			print(v + "\n")
-		}
-
-		byLen[l] = values
-
-		total += len(values)
-		if l < 8 {
-			short += len(values)
-		}
-	}
-
-	for l := 1; l <= 10; l++ {
-		values := byLen[l]
-		log.Printf("%d: %d", l, len(values))
-	}
-
-	log.Printf("total=%d", total)
-	log.Printf("short=%d", short)
-}
diff --git a/genseed/genseed.go b/genseed/genseed.go
index 7d2b56d..cd757d9 100644
--- a/genseed/genseed.go
+++ b/genseed/genseed.go
@@ -20,6 +20,8 @@ func main() {
 		return len(sample)
 	}))
 
+	dict := buildDictionary(samples, 1024)
+
 	def := state.NewState()
 	log.Printf("def=%d [%s]", totalLength(def, samples), def)
 
@@ -30,6 +32,66 @@ func main() {
 	log.Printf("opt=%d [%s]", totalLength(opt, samples), opt)
 }
 
+type pair struct {
+	symbol []byte
+	count  int
+}
+
+func buildDictionary(samples [][]byte, num int) [][]byte {
+	counts := map[uint64]*pair{}
+
+	for _, sample := range samples {
+		for i := 0; i < len(sample); i++ {
+			sub := sample[i:]
+			for j := 2; j < min(5, len(sub)); j++ {
+				sub2 := sub[:j]
+				k := toUint64(sub2)
+
+				p := counts[k]
+				if p == nil {
+					counts[k] = &pair{
+						symbol: sub2,
+						count:  1,
+					}
+				} else {
+					p.count++
+				}
+			}
+		}
+	}
+
+	pairs := []*pair{}
+
+	for _, p := range counts {
+		pairs = append(pairs, p)
+	}
+
+	slices.SortFunc(pairs, func(a, b *pair) int { return bytes.Compare(a.symbol, b.symbol) })
+	slices.SortStableFunc(pairs, func(a, b *pair) int { return b.score() - a.score() })
+
+	ret := [][]byte{}
+
+	for i := 0; i < num && i < len(pairs); i++ {
+		ret = append(ret, pairs[i].symbol)
+	}
+
+	return ret
+}
+
+func toUint64(bs []byte) uint64 {
+	var ret uint64
+
+	for _, b := range bs {
+		ret = (ret << 8) | uint64(b)
+	}
+
+	return ret
+}
+
+func (p pair) score() int {
+	return p.count * ((len(p.symbol) * 8) - 11)
+}
+
 func optimize(st *state.State, samples [][]byte) *state.State {
 	st.AddSymbol([]byte("it "))