Big update: Adding all advent of codes to same repo

AdventOfCode2020/day22/day22.go

@@ -0,0 +1,189 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"slices"
+	"strconv"
+	"strings"
+)
+
+type Queue struct {
+  arr []int
+  head uint
+  tail uint
+}
+
+func (s *Queue) Dequeue() int {
+  s.head++
+  return s.arr[s.head - 1]
+}
+
+func (s *Queue) Enqueue(num int) {
+  if len(s.arr) <= int(s.tail) {
+    s.arr = append(s.arr, num)
+  } else {
+    s.arr[s.tail] = num
+  }
+  s.tail++
+}
+
+func (s *Queue) Print() string {
+  str := ""
+  for i := s.head; i < s.tail; i++ {
+    str += strconv.Itoa(s.arr[i]) + ","
+  }
+  return str
+}
+
+func main() {
+  content, err := os.ReadFile("./input.txt")
+  if err != nil {
+    panic(err)
+  }
+
+  players := strings.Split(string(content), "\n\n")
+
+  player1 :=  strings.Split(players[0], "\n")[1:]
+  player2 := strings.Split(players[1], "\n")[1:]
+
+  player1Cards := Queue{
+    arr: make([]int, 0),
+    head: 0,
+    tail: 0,
+  }
+  player2Cards := Queue{
+    arr: make([]int, 0),
+    head: 0,
+    tail: 0,
+  }
+
+  for _, v := range player1 {
+    n, err := strconv.Atoi(v)
+    if err != nil {
+      panic(err)
+    }
+    player1Cards.Enqueue(n)
+  }
+
+  for _, v := range player2 {
+    if len(v) == 0 {
+      continue
+    }
+    n, err := strconv.Atoi(v)
+    if err != nil {
+      panic(err)
+    }
+    player2Cards.Enqueue(n)
+  }
+
+  /*
+  rounds := 0
+  for {
+    if player1Cards.head == player1Cards.tail  || player2Cards.head == player2Cards.tail {
+      break
+    }
+
+    player1Card := player1Cards.Dequeue()
+    player2Card := player2Cards.Dequeue()
+    if player1Card > player2Card {
+      player1Cards.Enqueue(player1Card)
+      player1Cards.Enqueue(player2Card)
+    } else {
+      player2Cards.Enqueue(player2Card)
+      player2Cards.Enqueue(player1Card)
+    }
+
+    rounds++
+  }
+
+  */
+
+  _, p1, p2 := PlayGame(player1Cards, player2Cards)
+
+  var winningScore uint = 0
+  if p1.tail - p1.head < p2.tail - p2.head {
+    for i := p2.head; i < p2.tail; i++ {
+      winningScore += (p2.tail - i) * uint(p2.arr[i])
+    }
+  } else {
+    for i := p1.head; i < p1.tail; i++ {
+      winningScore += (p1.tail - i) * uint(p1.arr[i])
+    }
+  }
+
+  fmt.Println(winningScore)
+}
+
+// true = player1, false = player2
+func PlayGame(player1 Queue, player2 Queue) (bool, *Queue, *Queue) {
+  cache1 := make(map[string]bool)
+  cache2 := make(map[string]bool)
+  for {
+    if player1.head == player1.tail  || player2.head == player2.tail {
+      return player2.head == player2.tail, &player1, &player2
+    }
+
+    // Before drawing, check.
+    player1string := player1.Print()
+    player2string := player2.Print()
+
+    _, exists := cache1[player1string]
+    if exists {
+      return true, &player1, &player2
+    }
+
+    _, exists = cache2[player2string]
+    if exists {
+      return true, &player1, &player2
+    }
+
+    cache1[player1string] = true
+    cache2[player2string] = true
+
+
+    player1Card := player1.Dequeue()
+    player2Card := player2.Dequeue()
+    
+    if int(player1.tail) - int(player1.head) >= player1Card && int(player2.tail) - int(player2.head) >= player2Card {
+      // Recursive case!
+      player1Copy := Queue{
+        arr: slices.Clone(player1.arr),
+        head: player1.head,
+        tail: player1.head + uint(player1Card),
+      }
+
+      player2Copy := Queue{
+        arr: slices.Clone(player2.arr),
+        head: player2.head,
+        tail: player2.head + uint(player2Card),
+      }
+
+      winner, _, _ := PlayGame(player1Copy, player2Copy)
+      if winner {
+        player1.Enqueue(player1Card)
+        player1.Enqueue(player2Card)
+      } else {
+        player2.Enqueue(player2Card)
+        player2.Enqueue(player1Card)
+      }
+    } else {
+      if player1Card > player2Card {
+        player1.Enqueue(player1Card)
+        player1.Enqueue(player2Card)
+      } else {
+        player2.Enqueue(player2Card)
+        player2.Enqueue(player1Card)
+      }
+    }
+  }
+
+}
+
+func GetString(arr []int) string {
+  s := ""
+  for _, v := range arr {
+    s += "," + strconv.Itoa(v)
+  }
+  return s
+}