add day-24 part1

day-24/internal/one/expression.go

@@ -0,0 +1,16 @@
+package one
+
+const (
+	AND = '&'
+	OR  = '|'
+	XOR = '^'
+)
+
+type expression struct {
+	left, right, target string
+	op                  rune
+}
+
+func newExpression(left, right, target string, op rune) expression {
+	return expression{left, right, target, op}
+}

day-24/internal/one/solve.go

@@ -0,0 +1,64 @@
+package one
+
+import (
+	"bytes"
+	"cmp"
+	"slices"
+	"strconv"
+	"strings"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func Solve(buf []byte) (int, error) {
+	r := bytes.NewReader(buf)
+	initial, wires, expressions, err := parseLines(r)
+	if err != nil {
+		return 0, err
+	}
+
+	for k, v := range initial {
+		wires[k] = v
+	}
+
+	wires = calculateWire(expressions, wires)
+
+	zWires := []zWire{}
+	for k, v := range wires {
+		if strings.HasPrefix(k, "z") {
+			zWires = append(zWires, zWire{k, v})
+		}
+	}
+	slices.SortFunc(zWires, func(a, b zWire) int {
+		return cmp.Compare(b.name, a.name)
+	})
+
+	var binStr strings.Builder
+	for _, zWire := range zWires {
+		binStr.WriteString(strconv.FormatInt(int64(zWire.value), 2))
+	}
+	log.Debug(binStr.String())
+
+	return mustConvBinToDec(binStr.String()), nil
+}
+
+func calculateWire(expressions []expression, wires map[string]int) map[string]int {
+	if !anyNegative(wires) {
+		return wires
+	}
+
+	for _, expression := range expressions {
+		if wires[expression.left] != noValue && wires[expression.right] != noValue {
+			switch expression.op {
+			case AND:
+				wires[expression.target] = wires[expression.left] & wires[expression.right]
+			case OR:
+				wires[expression.target] = wires[expression.left] | wires[expression.right]
+			case XOR:
+				wires[expression.target] = wires[expression.left] ^ wires[expression.right]
+			}
+		}
+	}
+
+	return calculateWire(expressions, wires)
+}

day-24/internal/one/solve_internal_test.go

@@ -0,0 +1,15 @@
+package one
+
+import (
+	_ "embed"
+	"os"
+	"testing"
+)
+
+//go:embed testdata/input.txt
+var data []byte
+
+func BenchmarkSolve(b *testing.B) {
+	os.Stdout, _ = os.Open(os.DevNull)
+	Solve(data)
+}

day-24/internal/one/util.go

@@ -0,0 +1,84 @@
+package one
+
+import (
+	"bufio"
+	"io"
+	"strconv"
+	"strings"
+)
+
+const (
+	left = iota * 2
+	right
+	target
+)
+
+func parseLines(r io.Reader) (map[string]int, map[string]int, []expression, error) {
+	initial := make(map[string]int)
+	wires := make(map[string]int)
+	expressions := []expression{}
+
+	var inGates bool
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		if line == "" {
+			inGates = true
+			continue
+		}
+
+		if inGates {
+			parts := strings.Split(line, " ")
+
+			wires[parts[left]] = noValue
+			wires[parts[right]] = noValue
+			wires[parts[target]] = noValue
+
+			var op rune
+			switch parts[1] {
+			case "AND":
+				op = AND
+			case "OR":
+				op = OR
+			case "XOR":
+				op = XOR
+			}
+			expressions = append(expressions, newExpression(parts[left], parts[right], parts[target], op))
+		} else {
+			parts := strings.Split(line, ": ")
+			initial[parts[0]] = mustConv(parts[1])
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, nil, nil, err
+	}
+
+	return initial, wires, expressions, nil
+}
+
+func mustConv(s string) int {
+	n, err := strconv.Atoi(s)
+	if err != nil {
+		panic(err)
+	}
+	return n
+}
+
+func anyNegative(wires map[string]int) bool {
+	for _, v := range wires {
+		if v == -1 {
+			return true
+		}
+	}
+	return false
+}
+
+func mustConvBinToDec(s string) int {
+	n, err := strconv.ParseInt(s, 2, 64)
+	if err != nil {
+		panic(err)
+	}
+	return int(n)
+}

day-24/internal/one/zwire.go

@@ -0,0 +1,8 @@
+package one
+
+const noValue = -1
+
+type zWire struct {
+	name  string
+	value int
+}