From da61e91642966ebdacdc5a86246c799f0a2894d3 Mon Sep 17 00:00:00 2001
From: Armin Friedl <dev@friedl.net>
Date: Tue, 7 Jan 2025 22:12:47 +0100
Subject: [PATCH] Day 23

---
 day23.py | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 day23.py

diff --git a/day23.py b/day23.py
new file mode 100644
index 0000000..6699b0e
--- /dev/null
+++ b/day23.py
@@ -0,0 +1,70 @@
+graph = [[0 for _ in range(26**2)] for _ in range(26**2)]
+
+edges = []
+
+with open("day23") as f:
+    for l in f:
+        (a,b) = l.strip().split('-')
+        x = (ord(a[0])-ord('a'))*26 + (ord(a[1])-ord('a'))
+        y = (ord(b[0])-ord('a'))*26 + (ord(b[1])-ord('a'))
+
+        graph[x][y] = 1
+        graph[y][x] = 1
+
+        edges.append((x,y))
+
+components = []
+for edge in edges:
+    a = edge[0]
+    b = edge[1]
+    for c, e in enumerate(graph[b]):
+        if e == 1 and graph[c][a] == 1:
+            components.append((a,b,c))
+
+t_components = set()
+for component in components:
+    for c in component:
+        if c >= 494 and c<520:
+            t_components.add(tuple(sorted(component)))
+
+print(len(t_components))
+
+
+def find_component(start):
+    component = [start[0],start[1]]
+
+    changed = True
+    while changed:
+        changed = False
+        a = component[-1]
+
+        candidates = []
+        for b, e in enumerate(graph[a]):
+            if e == 1: candidates.append(b)
+
+        for candidate in candidates:
+            for comp in component:
+                if graph[comp][candidate] != 1: break
+            else:
+                component.append(candidate)
+                changed = True
+    return component
+
+components = []
+for edge in edges:
+    components.append(find_component(edge))
+
+max_len = 0
+max_idx = -1
+for idx, c in enumerate(components):
+    if len(c) > max_len:
+        max_len = len(c)
+        max_idx = idx
+
+max_component = components[max_idx]
+max_component_alpha = []
+for mc in max_component:
+    a = chr(ord('a')+(mc//26))
+    b = chr(ord('a')+(mc%26))
+    max_component_alpha.append(a+b)
+print(','.join(sorted(max_component_alpha)))