Add solution day 24 part 1

Author: terminalnode

README.md

@@ -56,6 +56,6 @@ automatically rebuilt and redeployed every time the `common` module or their own
 | 08  | ⭐ ⭐      | 21  |          |
 | 09  | ⭐ ⭐      | 22  | ⭐ ⭐      |
 | 10  | ⭐ ⭐      | 23  | ⭐ ⭐      |
-| 11  | ⭐ ⭐      | 24  |          |
+| 11  | ⭐ ⭐      | 24  | ⭐        |
 | 12  | ⭐ ⭐      | 25  |          |
 | 13  | ⭐ ⭐      |     |          |

solutions/day24/main.go

@@ -1,9 +1,120 @@
 package main
 
 import (
+	"fmt"
 	"github.com/terminalnode/adventofcode2024/common"
+	"log"
+	"slices"
+	"strconv"
+	"strings"
 )
 
 func main() {
-	common.Setup(24, nil, nil)
+	common.Setup(24, part1, nil)
+}
+
+func part1(
+	input string,
+) string {
+	r, wm, err := parse(input)
+	if err != nil {
+		return fmt.Sprintf("Failed to parse input: %v", err)
+	}
+	zNames := findZIndexes(r, wm)
+	depSet := make(map[name]bool)
+	for _, zName := range zNames {
+		depSet[zName] = true
+	}
+
+	for len(depSet) > 0 {
+		newDepSet := make(map[name]bool)
+		for dep := range depSet {
+			depDeps, w := resolveDeps(r, wm, dep)
+			for _, depDep := range depDeps {
+				newDepSet[depDep] = true
+			}
+
+			if len(depDeps) == 1 {
+				w.execute(r)
+			}
+		}
+		depSet = newDepSet
+	}
+
+	zValues := make([]string, len(zNames))
+	for i, zName := range zNames {
+		if r[zName] {
+			zValues[i] = "1"
+		} else {
+			zValues[i] = "0"
+		}
+	}
+	slices.Reverse(zValues)
+	zString := strings.Join(zValues, "")
+	out, err := strconv.ParseInt(zString, 2, 0)
+	if err != nil {
+		return fmt.Sprintf("Failed to read %s as binary: %v", zString, err)
+	}
+
+	return fmt.Sprintf("Decimal output is %d (binary %s)", out, zString)
+}
+
+func resolveDeps(
+	r registry,
+	wm wireMap,
+	target name,
+) ([]name, wire) {
+	out := make([]name, 0, 3)
+	if _, ok := r[target]; ok {
+		return out, wire{}
+	}
+	out = append(out, target)
+
+	w, ok := wm[target]
+	if !ok {
+		log.Println("WARNING: target unresolvable", target)
+		return out, w
+	}
+
+	if _, ok := r[w.p1]; !ok {
+		out = append(out, w.p1)
+	}
+	if _, ok := r[w.p2]; !ok {
+		out = append(out, w.p2)
+	}
+
+	return out, w
+}
+
+func (w wire) execute(
+	r registry,
+) {
+	p1 := r[w.p1]
+	p2 := r[w.p2]
+	switch w.op {
+	case AND:
+		r[w.out] = p1 && p2
+	case OR:
+		r[w.out] = p1 || p2
+	case XOR:
+		r[w.out] = (p1 || p2) && (p1 != p2)
+	}
+}
+
+func findZIndexes(
+	r registry,
+	wm wireMap,
+) []name {
+	out := make([]name, 0, 30)
+	for curr := 0; ; curr++ {
+		key := name(fmt.Sprintf("z%02d", curr))
+		_, inR := r[key]
+		_, inWM := wm[key]
+		if !inR && !inWM {
+			break
+		}
+		out = append(out, key)
+	}
+	slices.Sort(out)
+	return out
 }

solutions/day24/parse.go

@@ -0,0 +1,106 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+)
+
+type name string
+type registry = map[name]bool
+type wireMap = map[name]wire
+
+type op int
+
+const (
+	AND = op(iota)
+	OR
+	XOR
+)
+
+type wire struct {
+	p1  name
+	op  op
+	p2  name
+	out name
+}
+
+func parse(
+	input string,
+) (registry, wireMap, error) {
+	rawRegistry, rawWires, err := splitInput(input)
+	outRegistry := make(registry)
+	outWires := make(wireMap)
+	if err != nil {
+		return outRegistry, outWires, err
+	}
+
+	for _, raw := range rawRegistry {
+		n, v, err := parseReg(raw)
+		if err != nil {
+			return outRegistry, outWires, err
+		}
+		outRegistry[n] = v
+	}
+
+	for _, raw := range rawWires {
+		w, err := parseWire(raw)
+		if err != nil {
+			return outRegistry, outWires, err
+		}
+		outWires[w.out] = w
+	}
+
+	return outRegistry, outWires, nil
+}
+
+func splitInput(
+	input string,
+) ([]string, []string, error) {
+	split := strings.Split(input, "\n\n")
+	if len(split) != 2 {
+		return []string{}, []string{}, fmt.Errorf("failed to split input, got %d parts", len(split))
+	}
+
+	return strings.Split(split[0], "\n"), strings.Split(split[1], "\n"), nil
+}
+
+func parseReg(
+	raw string,
+) (name, bool, error) {
+	split := strings.Split(raw, ": ")
+	if len(split) != 2 {
+		return "", false, fmt.Errorf("failed to split raw registry %s, got %d parts (%v)", raw, len(split), split)
+	} else if split[1] != "1" && split[1] != "0" {
+		return "", false, fmt.Errorf("failed to parse registry %s with initial value %s", raw, split[1])
+	}
+
+	return name(split[0]), split[1] == "1", nil
+}
+
+func parseWire(
+	raw string,
+) (wire, error) {
+	split := strings.Split(raw, " ")
+	if len(split) != 5 {
+		return wire{}, fmt.Errorf("failed to split raw wire %s, got %d parts (%v)", raw, len(split), split)
+	}
+
+	p1 := name(split[0])
+	rawOp := split[1]
+	p2 := name(split[2])
+	out := name(split[4])
+
+	var realOp op
+	switch rawOp {
+	case "AND":
+		realOp = AND
+	case "OR":
+		realOp = OR
+	case "XOR":
+		realOp = XOR
+	default:
+		return wire{}, fmt.Errorf("failed to parse operation %s", rawOp)
+	}
+
+	return wire{p1: p1, op: realOp, p2: p2, out: out}, nil
+}