Solve 2019 day 14 and 15

2019/d14.py

@@ -0,0 +1,83 @@
+from lib import get_data
+from math import ceil
+
+
+def ore_for_fuel(fuel_n, reactions_store):
+    ore_qty = 0
+    required = [(fuel_n, "FUEL")]
+    store = {}
+    while required:
+        required_qty, required_code = required.pop()
+        if required_code == "ORE":
+            ore_qty += required_qty
+            continue
+
+        if required_code in store:
+            if store[required_code] == required_qty:
+                del store[required_code]
+                continue
+            elif store[required_code] > required_qty:
+                store[required_code] -= required_qty
+                continue
+            elif store[required_code] < required_qty:
+                required_qty -= store[required_code]
+                del store[required_code]
+
+        inputs, output = reactions_store[required_code]
+        output_qty, output_code = output
+        assert required_code == output_code
+
+        # how often must this process be executed
+        n = ceil(required_qty / output_qty)
+
+        leftover_output_qty = n * output_qty - required_qty
+        assert leftover_output_qty >= 0
+
+        if leftover_output_qty > 0:
+            store[output_code] = leftover_output_qty
+
+        for qty_input, input_code in inputs:
+            required.append((qty_input * n, input_code))
+    return ore_qty
+
+
+def part_1(data):
+    reactions = []
+    to_get = {}
+    for line in data.splitlines():
+        left, right = line.split(" => ")
+        inputs = left.split(", ")
+        inputs = [(int(i.split()[0]), i.split()[1]) for i in inputs]
+        output = (int(right.split()[0]), right.split()[1])
+        reactions.append((inputs, output))
+        if output[1] in to_get:
+            assert False
+        else:
+            to_get[output[1]] = (inputs, output)
+
+    ore_qty = ore_for_fuel(1, to_get)
+    print(ore_qty)
+
+    min_fuel, max_fuel = 1, 100_000_000
+    target = 10**12  # trillion
+    while max_fuel - min_fuel > 1:
+        half_fuel = min_fuel + (max_fuel - min_fuel) // 2
+        ore_qty = ore_for_fuel(half_fuel, to_get)
+        if ore_qty < target:
+            min_fuel = half_fuel
+        elif ore_qty > target:
+            max_fuel = half_fuel
+        else:
+            min_fuel = half_fuel
+            max_fuel = half_fuel
+
+    print(min_fuel)
+
+
+def main():
+    data = get_data(__file__)
+    part_1(data)
+
+
+if __name__ == "__main__":
+    main()