2020 Day 22 Complete

2020/day22/input

@@ -0,0 +1,53 @@
+Player 1:
+4
+25
+3
+11
+2
+29
+41
+23
+30
+21
+50
+8
+1
+24
+27
+10
+42
+43
+38
+15
+18
+13
+32
+37
+34
+
+Player 2:
+12
+6
+36
+35
+40
+47
+31
+9
+46
+49
+19
+16
+5
+26
+39
+48
+7
+44
+45
+20
+17
+14
+33
+28
+22

2020/day22/main.go

@@ -0,0 +1,193 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+var debugLevel int
+
+const (
+	debugLo = 1
+	debugMd = 2
+	debugHi = 3
+	debugNo = -1
+)
+
+func main() {
+	fmt.Println("# Day 22")
+	inp := h.StdinToStringSlice()
+
+	debugLevel = h.Atoi(h.OptArgNumber(2, "-1"))
+
+	solve(inp, h.Atoi(h.OptArgNumber(1, "2")))
+}
+
+func print(s string, lvl int) {
+	if debugLevel != -1 && lvl >= debugLevel {
+		fmt.Print(s)
+	}
+}
+
+func solve(inp []string, part int) {
+	var player int
+	decks := make(map[int]*Deck)
+	for k := range inp {
+		if strings.TrimSpace(inp[k]) == "" {
+			continue
+		} else if strings.HasPrefix(inp[k], "Player ") {
+			player = h.Atoi(inp[k][7 : len(inp[k])-1])
+			decks[player] = &Deck{Player: player}
+			continue
+		} else {
+			decks[player].Add(h.Atoi(inp[k]))
+		}
+	}
+
+	if part == 1 {
+		solveNormal(decks[1], decks[2])
+	} else {
+		solveRecursive(decks[1], decks[2])
+	}
+}
+
+func solveNormal(deck1, deck2 *Deck) {
+	round := 1
+	winner := Winner(deck1, deck2)
+	for winner == -1 {
+
+		print(fmt.Sprintf("-- Round %d --\n%s\n%s\n", round, deck1, deck2), debugLo)
+
+		cmp1 := deck1.Draw()
+		cmp2 := deck2.Draw()
+		print(fmt.Sprintf("Player 1 plays: %d\nPlayer 2 plays: %d\n", cmp1, cmp2), debugLo)
+		if cmp1 > cmp2 {
+			print(fmt.Sprintln("Player 1 wins the round!"), debugLo)
+			deck1.Add(cmp1, cmp2)
+		} else if cmp2 > cmp1 {
+			print(fmt.Sprintln("Player 2 wins the round!"), debugLo)
+			deck2.Add(cmp2, cmp1)
+		}
+		round++
+		winner = Winner(deck1, deck2)
+	}
+	fmt.Printf("== Post-game results ==\n%s\n%s\n", deck1, deck2)
+	var score int
+	if winner == 1 {
+		score = deck1.Score()
+	} else {
+		score = deck2.Score()
+	}
+
+	fmt.Println("## Part 1:\nAnswer: ", score)
+}
+
+func solveRecursive(deck1, deck2 *Deck) {
+	winner := RPlayGame(deck1, deck2)
+
+	fmt.Printf("== Post-game results ==\n%s\n%s\n", deck1, deck2)
+	var score int
+	if winner == 1 {
+		score = deck1.Score()
+	} else {
+		score = deck2.Score()
+	}
+	fmt.Println("## Part 2:\nAnswer: ", score)
+}
+
+var totalGames int
+
+func RPlayGame(deck1, deck2 *Deck) int {
+	var history []string
+	var repeat bool
+	for deck1.Len() > 0 && deck2.Len() > 0 {
+		history, repeat = RPlayRound(deck1, deck2, history)
+		if repeat {
+			return 1
+		}
+	}
+	return Winner(deck1, deck2)
+}
+
+func RPlayRound(deck1, deck2 *Deck, history []string) ([]string, bool) {
+	status := fmt.Sprintf("%s%s", deck1, deck2)
+	if h.StringSliceContains(history, status) {
+		return history, true
+	}
+	nextHistory := append(history, status)
+	c1, c2 := deck1.Draw(), deck2.Draw()
+	if deck1.Len() >= c1 && deck2.Len() >= c2 {
+		winner := RPlayGame(deck1.Copy(c1), deck2.Copy(c2))
+		switch winner {
+		case 1:
+			deck1.Add(c1, c2)
+		case 2:
+			deck2.Add(c2, c1)
+		}
+		return nextHistory, false
+	}
+	if c1 > c2 {
+		deck1.Add(c1, c2)
+	} else {
+		deck2.Add(c2, c1)
+	}
+
+	return nextHistory, false
+}
+
+func Winner(deck1, deck2 *Deck) int {
+	if deck2.Empty() {
+		return 1
+	} else if deck1.Empty() {
+		return 2
+	}
+	return -1
+}
+
+type Deck struct {
+	Player int
+	cards  []int
+}
+
+func (d *Deck) Add(card ...int) {
+	d.cards = append(d.cards, card...)
+}
+
+func (d *Deck) Draw() int {
+	var ret int
+	ret, d.cards = d.cards[0], d.cards[1:]
+	return ret
+}
+
+func (d *Deck) Empty() bool {
+	return len(d.cards) == 0
+}
+
+func (d *Deck) Len() int {
+	return len(d.cards)
+}
+
+func (d *Deck) Score() int {
+	var ret int
+	for k := len(d.cards) - 1; k >= 0; k-- {
+		ret = ret + (d.cards[k] * (len(d.cards) - k))
+	}
+	return ret
+}
+
+func (d *Deck) Copy(num int) *Deck {
+	ret := Deck{
+		Player: d.Player,
+	}
+	for k := 0; k < num && k < len(d.cards); k++ {
+		ret.Add(d.cards[k])
+	}
+	return &ret
+
+}
+
+func (d Deck) String() string {
+	return fmt.Sprintf("Player %d's deck: %v", d.Player, d.cards)
+}

2020/day22/testinput

@@ -0,0 +1,13 @@
+Player 1:
+9
+2
+6
+3
+1
+
+Player 2:
+5
+8
+4
+7
+10

2020/day22/testinput2

@@ -0,0 +1,8 @@
+Player 1:
+43
+19
+
+Player 2:
+2
+29
+14