day 14

14/input.txt

@@ -0,0 +1,102 @@
+CKKOHNSBPCPCHVNKHFFK
+
+KO -> C
+SO -> S
+BF -> V
+VN -> B
+OV -> K
+VH -> O
+KV -> N
+KB -> F
+NB -> C
+HS -> K
+PF -> B
+HB -> N
+OC -> H
+FS -> F
+VV -> S
+KF -> C
+FN -> F
+KP -> S
+HO -> N
+NH -> K
+OO -> S
+FB -> C
+BP -> F
+CH -> N
+SN -> O
+KN -> B
+CV -> O
+CC -> B
+VB -> C
+PH -> V
+CO -> K
+KS -> K
+BK -> N
+FH -> S
+PV -> H
+CB -> P
+FO -> F
+BB -> K
+OB -> C
+HH -> F
+ON -> O
+FK -> B
+NF -> F
+SV -> F
+CP -> H
+SS -> B
+OP -> H
+NS -> O
+HK -> N
+BC -> P
+NV -> V
+VS -> F
+PC -> V
+CS -> F
+NP -> V
+PS -> F
+VC -> F
+KK -> S
+PO -> P
+HF -> H
+KC -> P
+SF -> N
+BV -> N
+FF -> V
+FV -> V
+BO -> N
+OS -> C
+OF -> H
+CN -> S
+NO -> O
+NC -> B
+VK -> C
+HN -> B
+PK -> N
+SK -> S
+HV -> F
+BH -> B
+OK -> S
+VO -> B
+BS -> H
+PP -> N
+SC -> K
+BN -> P
+FC -> S
+SB -> B
+SH -> H
+NN -> V
+NK -> N
+VF -> H
+CF -> F
+PB -> C
+SP -> P
+KH -> C
+VP -> N
+CK -> H
+HP -> P
+FP -> B
+HC -> O
+PN -> F
+OH -> H

14/main.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+)
+
+func main() {
+	file, err := os.Open("input.txt")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	scanner.Split(bufio.ScanLines)
+
+	insertions := make(map[string]string)
+	pairs := make(map[string]uint64)
+
+	var i int
+	var template string
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "" {
+			continue
+		}
+		if i == 0 {
+			template = line
+			for j := 0; j < len(template)-1; j++ {
+				pairs[string(template[j])+string(template[j+1])]++
+			}
+		} else {
+			var one, two, three rune
+			fmt.Sscanf(line, "%c%c -> %c", &one, &two, &three)
+			insertions[string(one)+string(two)] = string(three)
+		}
+		i++
+	}
+
+	var newPairs map[string]uint64
+
+	for j := 0; j < 40; j++ {
+		newPairs = make(map[string]uint64)
+		for pair, count := range pairs {
+			firstNewPair := string(pair[0]) + insertions[pair]
+			secondNewPair := insertions[pair] + string(pair[1])
+			newPairs[firstNewPair] += uint64(count)
+			newPairs[secondNewPair] += uint64(count)
+		}
+		pairs = newPairs
+		if j == 9 {
+			fmt.Println(count(&pairs))
+		}
+	}
+	fmt.Println(count(&pairs))
+}
+
+func count(pairs *map[string]uint64) uint64 {
+	counts := make(map[string]uint64)
+	for pair, count := range *pairs {
+		counts[string(pair[1])] += uint64(count)
+	}
+
+	var maxCount, minCount uint64 = 0, 0xffffffffffffffff
+
+	for _, total := range counts {
+		if total > maxCount {
+			maxCount = total
+		}
+		if total < minCount {
+			minCount = total
+		}
+	}
+
+	return maxCount - minCount
+}