feat: 2023 day 25

Author: Programator2

2023/25.py

@@ -0,0 +1,60 @@
+from aoc import *
+from collections import defaultdict
+from graphviz import Graph
+
+
+def search(node, m, visited):
+    if node in visited:
+        return
+    visited.add(node)
+    for n in m[node]:
+        search(n, m, visited)
+
+
+def main(input_file: str):
+    inp = lines(input_file)
+    dot = Graph()
+    m = defaultdict(set)
+    for l in inp:
+        left, right = l.rstrip().split(': ')
+        right = right.split()
+        dot.node(left)
+        for r in right:
+            dot.node(r)
+            dot.edge(left, r)
+
+            # These were added after inspecting the graph, see below.
+            if (
+                r == 'gbc'
+                and left == 'hxr'
+                or r == 'hxr'
+                and left == 'gbc'
+                or r == 'mvv'
+                and left == 'xkz'
+                or r == 'xkz'
+                and left == 'mvv'
+                or r == 'tmt'
+                and left == 'pnz'
+                or r == 'pnz'
+                and left == 'tmt'
+            ):
+                continue
+            m[r].add(left)
+            m[left].add(r)
+
+    # Store the graph as svg and identify nodes needed in Inkscape
+    # dot.format = 'svg'
+    # dot.render('25.dot')
+
+    v = set()
+    search('mvv', m, v)
+    a = len(v)
+    v = set()
+    search('xkz', m, v)
+    b = len(v)
+    return a * b
+
+
+DAY = 25
+FILE = f"{DAY}.txt"
+print(main(FILE))