Learning Go

2015 Day 19

2015/day-19/Makefile

@@ -0,0 +1,27 @@
+.DEFAULT_GOAL := all
+NAME = day-19-medicine-for-rudolph
+
+all: time-node time-go
+
+run-node:
+	node ./$(NAME).js
+
+time-node:
+	@echo "Timing Node...\n"
+	time -l node ./$(NAME).js
+	@echo ""
+
+run-go:
+	go run ./$(NAME).go
+
+go.out:
+	go build -o go.out ./$(NAME).go
+
+time-go: go.out
+	@echo "Timing Go...\n"
+	time -l ./go.out
+	@echo ""
+
+clean:
+	rm -f ./*.out
+	rm -f ./go.mod

2015/day-19/day-19-medicine-for-rudolph.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+)
+
+func main() {
+	f, _ := os.Open("./day-19-data.txt")
+	s := bufio.NewScanner(f)
+	rawInstructions := []string{}
+	for s.Scan() {
+		rawInstructions = append(rawInstructions, s.Text())
+	}
+
+	replacements, molecule := rawInstructions[:len(rawInstructions)-2], rawInstructions[len(rawInstructions)-1]
+
+	replacementMap := make(map[string][]string)
+	for _, r := range replacements {
+		from, to, _ := strings.Cut(r, " => ")
+		_, exists := replacementMap[from]
+		if exists {
+			replacementMap[from] = append(replacementMap[from], to)
+		} else {
+			replacementMap[from] = []string{to}
+		}
+	}
+
+	moleculeSet := make(map[string]struct{})
+	for k, v := range replacementMap {
+		for i := 0; i < len(molecule)-(len(k)-1); i++ {
+			sub := molecule[i : i+len(k)]
+			if sub == k {
+				for _, val := range v {
+					replaced := molecule[:i] + val + molecule[i+len(k):]
+					moleculeSet[replaced] = struct{}{}
+				}
+			}
+		}
+	}
+
+	fmt.Println("Part one:", len(moleculeSet))
+
+	r := regexp.MustCompile("[A-Z]")
+	numberOfMolecules := len(r.Split(molecule, -1)) - 1
+	r = regexp.MustCompile("Ar|Rn")
+	exteriorCantReplace := len(r.Split(molecule, -1)) - 1
+	r = regexp.MustCompile("Y")
+	interiorCantReplace := len(r.Split(molecule, -1)) - 1
+
+	fmt.Println("Part two:", numberOfMolecules-exteriorCantReplace-(2*interiorCantReplace)-1)
+}