day04

day04/day.go

@@ -1,13 +1,13 @@
 package day04
 
 import (
-	"fmt"
 	"regexp"
+	"sort"
 	"strconv"
 	"tools"
 )
 
-var roomRegexp = regexp.MustCompile(`^(.*)-([[:digit:]]+)\[(.*)\]$`)
+var roomRegexp = regexp.MustCompile(`^(.*)-([[:digit:]]+)\[(.*)]$`)
 
 func validateChecksum(roomname, checksum string) bool {
 	charcount := make(map[int32]int)
@@ -16,31 +16,71 @@ func validateChecksum(roomname, checksum string) bool {
 			charcount[c]++
 		}
 	}
-	for i, c := range checksum {
-		if i == 0 {
-			continue
+
+	charcountReverse := make(map[int]tools.ByteSlice)
+	counts := tools.NewSetInt()
+	for c, v := range charcount {
+		counts.Add(v)
+		charcountReverse[v] = append(charcountReverse[v], byte(c))
 	}
-		if c < int32(checksum[i-1]) || charcount[c] > charcount[int32(checksum[i-1])] {
-			return false
+
+	countList := counts.Keys()
+	sort.Sort(sort.Reverse(countList))
+
+	calcChecksum := ""
+	for _, v := range countList {
+		charList := charcountReverse[v]
+		sort.Sort(charList)
+		for _, c := range charList {
+			calcChecksum += string(c)
 		}
 	}
-	return true
+
+	return checksum == calcChecksum[:5]
 }
 
 func Part1(puzzle tools.AoCPuzzle) interface{} {
+	sectorSum := 0
 	for _, line := range puzzle.GetInputArray() {
 		roomMatches := roomRegexp.FindStringSubmatch(line)
 		roomName := roomMatches[1]
 		roomSectorId, _ := strconv.Atoi(roomMatches[2])
 		roomChecksum := roomMatches[3]
-		fmt.Println("Name:", roomName, "SectorID:", roomSectorId, "CheckSum:", roomChecksum)
-		if !validateChecksum(roomName, roomChecksum) {
-			fmt.Println("MEEP!")
+
+		if validateChecksum(roomName, roomChecksum) {
+			sectorSum += roomSectorId
 		}
 	}
-	return 0
+
+	return sectorSum
 }
 
 func Part2(puzzle tools.AoCPuzzle) interface{} {
-	return 0
+	for _, line := range puzzle.GetInputArray() {
+		roomMatches := roomRegexp.FindStringSubmatch(line)
+		roomName := roomMatches[1]
+		roomSectorId, _ := strconv.Atoi(roomMatches[2])
+		roomChecksum := roomMatches[3]
+
+		if validateChecksum(roomName, roomChecksum) {
+			addNum := int32(roomSectorId) % 26
+			realName := ""
+			for _, c := range roomName {
+				switch c {
+				case '-':
+					realName += " "
+				default:
+					for c+addNum > 122 {
+						c -= 26
+					}
+					realName += string(c + addNum)
+				}
+			}
+			if realName == "northpole object storage" {
+				return roomSectorId
+			}
+		}
+	}
+
+	return -1
 }