Implement 2019 day 14

2019/aoc2019/day14.py

@@ -0,0 +1,71 @@
+import math
+from collections import defaultdict
+from typing import TextIO, Tuple
+
+from networkx import DiGraph, topological_sort
+
+
+def read_pair(item: str) -> Tuple[str, int]:
+    amount, element = item.split(' ')
+
+    return element, int(amount)
+
+
+def read_recipes(data: TextIO) -> DiGraph:
+    graph = DiGraph()
+
+    for line in data:
+        requisites, production = line.strip().split(' => ')
+
+        produced, produced_amount = read_pair(production)
+        graph.add_node(produced, weight=produced_amount)
+
+        for requisite in requisites.split(', '):
+            required, required_amount = read_pair(requisite)
+            graph.add_edge(produced, required, weight=required_amount)
+
+    return graph
+
+
+def ore_required(graph: DiGraph, fuel_required: int) -> int:
+    requirements = defaultdict(int)
+    requirements['FUEL'] = fuel_required
+
+    for element in topological_sort(graph):
+        if element not in requirements:
+            continue
+
+        if element == 'ORE':
+            break
+
+        element_produced = graph.nodes[element]['weight']
+        productions_required = math.ceil(requirements[element] / element_produced)
+
+        for _, elem_required, amount_required in graph.edges(element, data='weight'):
+            requirements[elem_required] += amount_required * productions_required
+
+    return requirements['ORE']
+
+
+def part1(data: TextIO) -> int:
+    return ore_required(read_recipes(data), 1)
+
+
+def part2(data: TextIO) -> int:
+    ore_available = 1000000000000
+    graph = read_recipes(data)
+
+    min_possible = 1  # lower bound of ORE / ore_required(graph, 1) exists but is slower
+    max_possible = ore_available
+
+    while min_possible != max_possible:
+        check = min_possible + (max_possible - min_possible + 1) // 2
+
+        required = ore_required(graph, check)
+
+        if required <= ore_available:
+            min_possible = check
+        else:
+            max_possible = check - 1
+
+    return min_possible