day4, example

day4/dayFour.go

@@ -0,0 +1,110 @@
+package day4
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func Run() int {
+	fmt.Println("in day 4")
+	cards := ReadAllCards()
+	result := 0
+
+	for _, card := range cards {
+		fmt.Printf("> checking card %+v with points %d", card, card.GetPoints())
+		result += card.GetPoints()
+	}
+
+	return result
+}
+
+type Card struct {
+	Title int
+	WinningNums []int
+	OwnNums []int
+}
+
+func ReadAllCards() []Card {
+	filename := "day4/example"
+	bytes, err := os.ReadFile(filename)
+	if err != nil {
+		panic(fmt.Sprintf("can't read file %s", filename))
+	}
+	text := string(bytes)
+	lines := strings.Split(text, "\n")
+	result := make([]Card, len(lines))
+
+	for _, line := range lines {
+		if line == "" {
+			continue
+		}
+		result = append(result, ReadCard(line))
+	}
+
+	return result
+}
+
+// read line like 'Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53'
+func ReadCard(line string) Card {
+	result := Card{}
+	extractingTitle := strings.Split(line, ":")
+	title := extractingTitle[0]
+	numberPart := extractingTitle[1]
+
+	titleNumStr := strings.Split(title, " ")[1]
+	titleNum, err := strconv.Atoi(titleNumStr)
+	if err != nil {
+		panic(fmt.Sprintf("error extracting card title: %s, %s", line, titleNumStr))
+	}
+	result.Title = titleNum
+
+	extractingNumbers := strings.Split(numberPart, "|")
+	for _, winningNumStr := range strings.Split(  extractingNumbers[0], " " ) {
+		winningNumStr = strings.TrimSpace(winningNumStr)
+		if winningNumStr == "" {
+			continue
+		}
+		winningNum, err := strconv.Atoi(winningNumStr)
+		if err != nil {
+			panic(fmt.Sprintf("error extracting winning card num: %s from  '%s'", line, winningNumStr))
+		}
+		result.WinningNums = append(result.WinningNums, winningNum)
+	}
+	for _, ownNumStr := range strings.Split(  extractingNumbers[1], " " ) {
+		ownNumStr = strings.TrimSpace(ownNumStr)
+		if ownNumStr == "" {
+			continue
+		}
+		ownNum, err := strconv.Atoi(ownNumStr)
+		if err != nil {
+			panic(fmt.Sprintf("error extracting own card num: %s, %s", line, ownNumStr))
+		}
+		result.OwnNums = append(result.OwnNums, ownNum)
+	}
+
+	return result
+}
+
+func (c *Card)GetPoints() int {
+	winningSet := make(map[int]any)
+	for _, winNum := range c.WinningNums {
+		winningSet[winNum] = struct{}{}
+	}
+
+	result := 0
+	hasMatch := false
+	for _, ownNum := range c.OwnNums {
+		_, isWinning := winningSet[ownNum]
+		if isWinning {
+			if !hasMatch {
+				result = 1
+				hasMatch = true
+			} else {
+				result *= 2
+			}
+		}
+	}
+	return result
+}

day4/example

@@ -0,0 +1,6 @@
+Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53
+Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19
+Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1
+Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83
+Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36
+Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11

main.go

@@ -3,11 +3,11 @@ package main
 import (
 	"log"
 
-	"sunshine.industries/aoc2023/day3"
+	"sunshine.industries/aoc2023/day4"
 )
 
 func main() {
 	log.Print("> starting run:")
-	result := day3.Run()
-	log.Printf("day3 result: %d", result)
+	result := day4.Run()
+	log.Printf("day4 result: %d\n****\n", result)
 }