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