day-24/internal/one/solve.go

@@ -2,8 +2,8 @@ package one
 
 import (
 	"bytes"
-	"math"
 	"sort"
+	"strconv"
 	"strings"
 )
 
@@ -20,12 +20,12 @@ func Solve(buf []byte) (int, error) {
 	})
 	sort.Sort(byName(zWires))
 
-	var decimal int
+	var binStr strings.Builder
-	for i, zWire := range zWires {
+	for _, zWire := range zWires {
-		decimal += zWire.value * int(math.Pow(float64(2), float64(i)))
+		binStr.WriteString(strconv.Itoa(zWire.value))
 	}
 
-	return decimal, nil
+	return mustConvBinToDec(binStr.String()), nil
 }
 
 func calculateWire(expressions []expression, wires map[string]int) map[string]int {

day-24/internal/one/util.go

@@ -79,6 +79,14 @@ func anyNegative(wires map[string]int) bool {
 	return false
 }
 
+func mustConvBinToDec(s string) int {
+	n, err := strconv.ParseInt(s, 2, 64)
+	if err != nil {
+		panic(err)
+	}
+	return int(n)
+}
+
 func filter(wires map[string]int, fn func(string) bool) []zWire {
 	var filtered []zWire
 	for name, value := range wires {

day-24/internal/one/zwire.go

@@ -7,11 +7,9 @@ type byName []zWire
 func (b byName) Len() int {
 	return len(b)
 }
-
 func (b byName) Less(i, j int) bool {
-	return b[i].name < b[j].name
+	return b[j].name < b[i].name
 }
-
 func (b byName) Swap(i, j int) {
 	b[i], b[j] = b[j], b[i]
 }