2024

2024/05/main.py

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+from typing import List, Union, Tuple, Set
+from dataclasses import dataclass
+import networkx as nx
+import matplotlib.pyplot as plt
+
+
+@dataclass
+class Node:
+    id: int
+    links: List
+
+
+@dataclass
+class Manual:
+    rules: Tuple[int]
+    updates: Tuple[int]
+
+    def check_update(self, update: Tuple[int]) -> bool:
+        cur = 0
+        for n in update:
+            if n not in self.order:
+                continue
+            m = self.order[n]
+            if m < cur:
+                return False
+            cur = m
+        return True
+
+    def check(self):
+        total = 0
+        for update in self.updates:
+            valid = self.check_update(update)
+            if valid:
+                total += update[len(update) // 2]
+        return total
+
+    def build_rules(self):
+        unique: Set[int] = set()
+        for rule in self.rules:
+            unique.add(rule[0])
+            unique.add(rule[1])
+        nodes = {n: Node(id=n, links=[]) for n in unique}
+        for start, end in self.rules:
+            nodes[start].links.append(end)
+
+        # Test
+        G = nx.DiGraph()
+        for rule in self.rules:
+            G.add_edge(*rule)
+        print(G.number_of_nodes())
+
+        TR = nx.transitive_reduction(G)
+        subax1 = plt.subplot(121)
+        nx.draw(TR, with_labels=True, font_weight="bold")
+        plt.show()
+
+        sorted = list(nx.topological_sort(G))
+        print(sorted)
+
+        # Topological sorting
+        # https://cs.stackexchange.com/a/29133
+        order = {n: i for i, n in enumerate(sorted)}
+        self.order = order
+
+    @staticmethod
+    def parse(raw: str):
+        rules_raw, updates_raw = raw.strip().split("\n\n")
+        rules = [tuple((map(int, line.split("|")))) for line in rules_raw.splitlines()]
+        updates = [
+            tuple(map(int, line.split(","))) for line in updates_raw.splitlines()
+        ]
+        return Manual(rules, updates)
+
+
+def solve(raw: str) -> int:
+    # Part 1
+    part1 = 0
+    part2 = 0
+
+    m = Manual.parse(raw)
+    m.build_rules()
+    part1 = m.check()
+
+    return (part1, part2)
+
+
+# Test
+with open("./2024/05/test.txt", "r") as f:
+    result = solve(f.read().strip())
+    print(result)
+
+# Input
+with open("./2024/05/input.txt", "r") as f:
+    result = solve(f.read().strip())
+    print(result)