1 files changed, 59 insertions, 0 deletions
diff --git a/day21.py b/day21.py
new file mode 100644
index 0000000..c09cd9a
--- /dev/null
+++ b/day21.py
@@ -0,0 +1,59 @@
+#!/usr/bin/env python
+
+from itertools import product
+from collections import namedtuple
+from math import ceil
+
+Item = namedtuple('Item', ['cost', 'damage', 'armor'])
+Character = namedtuple('Character', ['hp', 'damage', 'armor'])
+weapons = [
+    Item(8, 4, 0),
+    Item(10, 5, 0),
+    Item(25, 6, 0),
+    Item(40, 7, 0),
+    Item(74, 8, 0)
+]
+
+armor = [
+    Item(0, 0, 0),
+    Item(13, 0, 1),
+    Item(31, 0, 2),
+    Item(53, 0, 3),
+    Item(75, 0, 4),
+    Item(102, 0, 5)
+]
+
+rings = [
+    Item(25, 1, 0),
+    Item(50, 2, 0),
+    Item(100, 3, 0),
+    Item(20, 0, 1),
+    Item(40, 0, 2),
+    Item(80, 0, 3),
+    Item(0, 0, 0),
+    Item(0, 0, 0)
+]
+
+def willWin(player, boss):
+    playerMoves = ceil(player.hp / max(boss.damage - player.armor, 1))
+    bossMoves = ceil(boss.hp / max(player.damage - boss.armor, 1))
+    return playerMoves >= bossMoves
+
+boss = Character(103, 9, 2)
+winningCosts = []
+losingCosts = []
+for weapon, shield, ring1, ring2 in product(weapons, armor, rings, rings):
+    if ring1.cost == ring2.cost and ring1.cost != 0: continue
+    totalCost = weapon.cost + shield.cost + ring1.cost + ring2.cost
+    totalDamage = weapon.damage + shield.damage + ring1.damage + ring2.damage
+    totalArmor = weapon.armor + shield.armor + ring1.armor + ring2.armor
+    player = Character(100, totalDamage, totalArmor)
+    if willWin(player, boss):
+        winningCosts.append(totalCost)
+    else:
+        losingCosts.append(totalCost)
+
+# part 1
+print(min(winningCosts))
+# part 2
+print(max(losingCosts))