[Python/2019] Restructure solutions

Python/2019/14.py

@@ -0,0 +1,86 @@
+from lib import *
+
+input = read_input(2019, 14)
+
+
+def ceil(a, b):
+    return a // b + (a % b > 0)
+
+
+reactions = {}
+for line in input.splitlines():
+    reactants, product = line.split(" => ")
+    reactants = [reactant.split() for reactant in reactants.split(", ")]
+    amount, product = product.split()
+    assert product not in reactions
+    reactions[product] = ([(reactant, int(amount)) for amount, reactant in reactants], int(amount))
+
+ore_used = 0
+chemicals = {}
+Q = [("FUEL", 1)]
+while Q:
+    chemical, prod_amount = Q.pop(0)
+    if chemical == "ORE":
+        ore_used += prod_amount
+        continue
+    chem_amount = chemicals.get(chemical, 0)
+    reaction_amount = prod_amount - chem_amount
+    if reaction_amount <= 0:
+        chemicals[chemical] -= prod_amount
+        continue
+    reactants, product_amount = reactions[chemical]
+    reaction_count = ceil(reaction_amount, product_amount)
+    for reactant, amount in reactants:
+        Q.append((reactant, amount * reaction_count))
+    chemicals[chemical] = chem_amount + reaction_count * product_amount - prod_amount
+print(ore_used)
+
+
+def ceil(a, b):
+    return a // b + (a % b > 0)
+
+
+reactions = {}
+for line in input.splitlines():
+    reactants, product = line.split(" => ")
+    reactants = [reactant.split() for reactant in reactants.split(", ")]
+    amount, product = product.split()
+    assert product not in reactions
+    reactions[product] = ([(reactant, int(amount)) for amount, reactant in reactants], int(amount))
+
+
+def get_ore_used(amount):
+    ore_used = 0
+    chemicals = {}
+    Q = [("FUEL", amount)]
+    while Q:
+        chemical, prod_amount = Q.pop(0)
+        if chemical == "ORE":
+            ore_used += prod_amount
+            continue
+        chem_amount = chemicals.get(chemical, 0)
+        reaction_amount = prod_amount - chem_amount
+        if reaction_amount <= 0:
+            chemicals[chemical] -= prod_amount
+            continue
+        reactants, product_amount = reactions[chemical]
+        reaction_count = ceil(reaction_amount, product_amount)
+        for reactant, amount in reactants:
+            Q.append((reactant, amount * reaction_count))
+        chemicals[chemical] = chem_amount + reaction_count * product_amount - prod_amount
+    return ore_used
+
+
+LIMIT = 1000000000000
+low = 0
+high = LIMIT
+while low < high:
+    guess = (low + high) // 2
+    used = get_ore_used(guess)
+    if used <= LIMIT:
+        if get_ore_used(guess + 1) > LIMIT:
+            print(guess)
+            break
+        low = guess
+    elif used > LIMIT:
+        high = guess