(s, eeelefant)

1 files changed, 52 insertions, 0 deletions

diff --git a/2023/20/solve.py b/2023/20/solve.py
new file mode 100644
index 0000000..c474654
--- /dev/null
+++ b/2023/20/solve.py
@@ -0,0 +1,52 @@
+L = [
+    (m := l.strip().split(" -> ")) and (m[0][1:], (m[0][0], m[1].split(", ")))
+    for l in open("input").readlines()
+]
+L = dict(L)
+
+state = {}
+
+# init conjunctions to low pulse
+for s, (_, ds) in L.items():
+    for d in ds:
+        k = ("&", d)
+        if k not in state:
+            state[k] = {}
+        state[k][s] = False
+
+rx = {k: 0 for k in state[("&", list(state[("&", "rx")].keys())[0])]}
+
+for i in range(1, 424242):
+    q = [("seeelefant", "roadcaster", False)]
+
+    while q:
+        s, m, p = q.pop(0)
+        state[p] = state.get(p, 0) + 1
+
+        if m not in L:
+            continue
+
+        k, ds = L[m]
+        if k == "%":
+            if p:
+                continue
+            else:
+                state[(k, m)] = not state.get((k, m), False)
+                p = state[(k, m)]
+        elif k == "&":
+            state[(k, m)][s] = p
+            p = any(not x for x in state[(k, m)].values())
+
+            if s in rx.keys():
+                for _k in state[(k, m)].keys():
+                    if state[(k, m)][_k]:
+                        rx[_k] = i
+
+        for d in ds:
+            q.append((m, d, p))
+
+    if i == 1000:  # part 1
+        print(state[True] * state[False])
+    if all(rx.values()):  # part 2
+        print(eval("*".join(str(n) for n in rx.values())))
+        break