From f5df4c2e4ae0a59ec2fb0749d4e9fb4df00f4255 Mon Sep 17 00:00:00 2001
From: Alfred Melch <dev@melch.pro>
Date: Wed, 23 Dec 2020 14:53:08 +0100
Subject: [PATCH] Solve 2020/22

---
 2020/22/example      | 13 +++++++++
 2020/22/example2     |  9 ++++++
 2020/22/input        | 53 +++++++++++++++++++++++++++++++++++
 2020/22/solution1.py | 38 +++++++++++++++++++++++++
 2020/22/solution2.py | 66 ++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 179 insertions(+)
 create mode 100644 2020/22/example
 create mode 100644 2020/22/example2
 create mode 100644 2020/22/input
 create mode 100644 2020/22/solution1.py
 create mode 100644 2020/22/solution2.py

diff --git a/2020/22/example b/2020/22/example
new file mode 100644
index 0000000..391cd24
--- /dev/null
+++ b/2020/22/example
@@ -0,0 +1,13 @@
+Player 1:
+9
+2
+6
+3
+1
+
+Player 2:
+5
+8
+4
+7
+10
diff --git a/2020/22/example2 b/2020/22/example2
new file mode 100644
index 0000000..b0fae37
--- /dev/null
+++ b/2020/22/example2
@@ -0,0 +1,9 @@
+Player 1:
+43
+19
+
+Player 2:
+2
+29
+14
+
diff --git a/2020/22/input b/2020/22/input
new file mode 100644
index 0000000..4aed5fe
--- /dev/null
+++ b/2020/22/input
@@ -0,0 +1,53 @@
+Player 1:
+31
+24
+5
+33
+7
+12
+30
+22
+48
+14
+16
+26
+18
+45
+4
+42
+25
+20
+46
+21
+40
+38
+34
+17
+50
+
+Player 2:
+1
+3
+41
+8
+37
+35
+28
+39
+43
+29
+10
+27
+11
+36
+49
+32
+2
+23
+19
+9
+13
+15
+47
+6
+44
diff --git a/2020/22/solution1.py b/2020/22/solution1.py
new file mode 100644
index 0000000..e89b47d
--- /dev/null
+++ b/2020/22/solution1.py
@@ -0,0 +1,38 @@
+
+from collections import deque
+
+
+p1 = deque()
+p2 = deque()
+
+
+with open('input', 'r') as f:
+    f.readline()  # player 1
+    while (line := f.readline()) and line != '\n':
+        p1.append(int(line))
+    f.readline()  # player 2
+    while (line := f.readline()) and line != '\n':
+        p2.append(int(line))
+
+
+print(p1)
+print(p2)
+
+while len(p1) and len(p2):
+    a = p1.popleft()
+    b = p2.popleft()
+    winner = p1 if a > b else p2
+    winner.append(max(a, b))
+    winner.append(min(a, b))
+
+print(p1)
+print(p2)
+
+winner = p1 if len(p1) else p2
+i = 1
+score = 0
+while len(winner):
+    score += winner.pop() * i
+    i += 1
+
+print(score)
diff --git a/2020/22/solution2.py b/2020/22/solution2.py
new file mode 100644
index 0000000..01a7863
--- /dev/null
+++ b/2020/22/solution2.py
@@ -0,0 +1,66 @@
+
+from collections import deque
+
+
+p1 = deque()
+p2 = deque()
+
+
+with open('input', 'r') as f:
+    f.readline()  # player 1
+    while (line := f.readline()) and line != '\n':
+        p1.append(int(line))
+    f.readline()  # player 2
+    while (line := f.readline()) and line != '\n':
+        p2.append(int(line))
+
+print('p1:', p1)
+print('p2:', p2)
+
+
+def game(p1, p2):
+    rounds = set()
+    while len(p1) and len(p2):
+        # prevent infinite games
+        round_hash = str(p1) + str(p2)
+        if round_hash in rounds:
+            return 1
+        rounds.add(round_hash)
+
+        a = p1.popleft()
+        b = p2.popleft()
+
+        # check if each player has enough cards for recursion
+        if len(p1) >= a and len(p2) >= b:
+            new_p1 = p1.copy()
+            new_p2 = p2.copy()
+            while len(new_p1) > a:
+                new_p1.pop()
+            while len(new_p2) > b:
+                new_p2.pop()
+            winner = game(new_p1, new_p2)
+        else:
+            # normal round
+            winner = 1 if a > b else 2
+
+        # append cards to winner
+        winning_player = p1 if winner == 1 else p2
+        winning_player.append(a if winner == 1 else b)
+        winning_player.append(b if winner == 1 else a)
+    return 1 if len(p1) else 2
+
+
+game(p1, p2)
+
+print('After game:')
+print('p1:', p1)
+print('p2:', p2)
+winner = p1 if len(p1) else p2
+i = 1
+score = 0
+while len(winner):
+    score += winner.pop() * i
+    i += 1
+
+print('Score:')
+print(score)