2021 - Day 14 (Improved implementation)

2021/14/improved.go

@@ -0,0 +1,94 @@
+package main
+
+import (
+	aoc "AoC/2021/common"
+	"bufio"
+	"strings"
+)
+
+func synthesis(input *bufio.Scanner, steps int) int {
+	// Read template
+	input.Scan()
+	polymer := input.Text()
+
+	// Skip empty line
+	input.Scan()
+
+	// Create the mapping
+	subs := make(map[string]string, 0)
+	for input.Scan() {
+		line := input.Text()
+		s := strings.Split(line, " ")
+
+		subs[s[0]] = s[2]
+	}
+
+	// Count the amount of each letter and pair in the template
+	pairs := make(map[string]int, 0)
+	counter := make(map[string]int, 0)
+	for i := 0; i < len(polymer); i++ {
+		if i < len(polymer)-1 {
+			pairs[string(polymer[i]) + string(polymer[i+1])]++
+		}
+		counter[string(polymer[i])]++
+	}
+
+	// Execute each step
+	for step := 1; step <= steps; step++ {
+		pairsNew := make(map[string]int, 0)
+		for p, c := range pairs {
+			// Each pair will form two new pairs after insertion
+			pairsNew[string(p[0]) + subs[p]] += c
+			pairsNew[subs[p] + string(p[1])] += c
+			counter[subs[p]] += c
+		}
+
+		pairs = pairsNew
+	}
+
+
+	min := -1
+	max := -1
+	for _, c := range counter {
+		if c < min || min == -1 {
+			min = c
+		}
+
+		if c > max || max == -1 {
+			max = c
+		}
+	}
+
+	return max - min
+}
+
+func main() {
+	challenge := aoc.New(2021, 14)
+
+	challenge.Test(`NNCB
+
+CH -> B
+HH -> N
+CB -> H
+NH -> C
+HB -> C
+HC -> B
+HN -> C
+NN -> C
+BH -> H
+NC -> B
+NB -> B
+BN -> B
+BB -> N
+BC -> B
+CC -> N
+CN -> C`, []int{1588, 2188189693529})
+
+	challenge.Solution(1, func (input *bufio.Scanner) int {
+		return synthesis(input, 10)
+	})
+
+	challenge.Solution(2, func (input *bufio.Scanner) int {
+		return synthesis(input, 40)
+	})
+}