Combine AoC Repos

2015/day19/main.go

@@ -0,0 +1,123 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	var input []string
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		input = append(input, scanner.Text())
+	}
+
+	transforms := make(map[string][]string)
+	var stMolecule string
+
+	for i := range input {
+		if strings.Contains(input[i], "=>") {
+			parts := strings.Split(input[i], " => ")
+			transforms[parts[0]] = append(transforms[parts[0]], parts[1])
+		} else if len(input[i]) > 0 {
+			// Must be the calibration molecule
+			stMolecule = input[i]
+		}
+	}
+
+	fmt.Println("*** CALIBRATION ***")
+	res := calibrate(stMolecule, transforms)
+	fmt.Println("Found " + strconv.Itoa(len(res)) + " combinations")
+	fmt.Println("\n")
+	fmt.Println("*** MANUFACTURING ***")
+	backTrans := reverseTransforms(transforms)
+	manufacture(stMolecule, backTrans, 0)
+}
+
+// stepBack takes an ending string and a reversed list of the transformations
+func manufacture(molecule string, transforms map[string][]string, steps int) {
+	fmt.Println(molecule)
+
+	if molecule == "e" {
+		fmt.Println("Found in " + strconv.Itoa(steps) + " steps")
+		os.Exit(0)
+	}
+
+	for k, v := range transforms {
+		if strings.Contains(molecule, k) {
+			for i := range v {
+				tstVal := strings.Replace(molecule, k, v[i], 1)
+				manufacture(tstVal, transforms, steps+1)
+			}
+		}
+	}
+}
+
+func reverseTransforms(t map[string][]string) map[string][]string {
+	ret := make(map[string][]string)
+	for v := range t {
+		for j := range t[v] {
+			ret[t[v][j]] = append(ret[t[v][j]], v)
+		}
+	}
+	return ret
+}
+
+func calibrate(molecule string, transforms map[string][]string) []string {
+	var ret []string
+	atoms := getAtomsFromMolecule(molecule)
+
+	for i := range atoms {
+		// Build a string of atoms before i
+		start := strings.Join(atoms[:i], "")
+		// And all after i too
+		end := strings.Join(atoms[i+1:], "")
+		// Find all transforms for atoms[i]
+		if v, ok := transforms[atoms[i]]; ok {
+			for j := range v {
+				ret = uniqueInsert(ret, start+v[j]+end)
+				//ret = append(ret, start+v[j]+end)
+			}
+		}
+	}
+	return ret
+}
+
+func getAtomsFromMolecule(molecule string) []string {
+	var atoms []string
+	var bldAtom string
+
+	for i := range molecule {
+		if molecule[i] >= 'A' && molecule[i] <= 'Z' {
+			if len(bldAtom) > 0 {
+				atoms = append(atoms, bldAtom)
+			}
+			bldAtom = string(molecule[i])
+			continue
+		}
+		bldAtom = bldAtom + string(molecule[i])
+	}
+	return append(atoms, bldAtom)
+}
+
+func uniqueInsert(curr []string, ins string) []string {
+	for i := range curr {
+		if curr[i] == ins {
+			return curr
+		}
+	}
+	return append(curr, ins)
+}
+
+func mustAtoi(s string) int {
+	var i int
+	var err error
+	if i, err = strconv.Atoi(s); err != nil {
+		fmt.Println("Tried to atoi " + s)
+		os.Exit(1)
+	}
+	return i
+}