Day 16

Leaderboard was super quick for part 1 today! I had a small bug in my
part 1 code, but even without it, I would've missed the leaderboard. 🤷‍♂️

Author: BarrensZeppelin

16.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env pypy3
+# 161/39
+from __future__ import annotations
+
+from util import *
+
+replace_stdin()
+
+res = 0
+
+G = Grid(lines())
+
+s = G.rev["S"][0]
+e = G.rev["E"][0]
+
+def adj(p):
+    p, d = p
+
+    np = p + DIR_NORTHNEG[d]
+    if G(np) in ".E":
+        yield (np, d), 1
+
+    yield (p, (d + 1) % 4), 1000
+    yield (p, (d - 1) % 4), 1000
+    # for i in range(4):
+    #     d = (d + 1) % 4
+    #     yield
+
+dists, prevs = dijkstra(adj, (s, 0))
+
+res = min(d for p, d in dists.items() if p[0] == e)
+md = res
+
+_, Q, _ = bfs(prevs, *((e, i) for i in range(4)))
+
+res = len({p for p, _ in Q})
+
+submit(res)