From 2ee16eb1ba4dfd71576f19e71b248e34e31f646d Mon Sep 17 00:00:00 2001
From: felixm <mail@felixm.de>
Date: Wed, 25 Dec 2024 12:14:04 -0500
Subject: [PATCH] Solve 2024 day 24

---
 2024/d24.py | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 README.md   |   5 +-
 2 files changed, 146 insertions(+), 2 deletions(-)
 create mode 100644 2024/d24.py

diff --git a/2024/d24.py b/2024/d24.py
new file mode 100644
index 0000000..1126738
--- /dev/null
+++ b/2024/d24.py
@@ -0,0 +1,143 @@
+from lib import get_data
+from lib import ints
+
+LHS, OP, RHS, _, OUT = 0, 1, 2, 3, 4
+
+
+def run(states, gates):
+    change = True
+    while change:
+        change = False
+        for gate in gates:
+            i1, op, i2, _, out = gate
+            if i1 in states and i2 in states and out not in states:
+                change = True
+                outv = None
+                match op:
+                    case "OR":
+                        outv = states[i1] | states[i2]
+                    case "XOR":
+                        outv = states[i1] ^ states[i2]
+                    case "AND":
+                        outv = states[i1] & states[i2]
+                assert outv is not None
+                states[out] = outv
+
+    i, t = 0, 0
+    while True:
+        si = f"z{i:02}"
+        if not si in states:
+            break
+        if states[si]:
+            t += 2**i
+        i += 1
+    return t
+
+
+data = get_data(__file__)
+
+s1, s2 = data.split("\n\n")
+states = {}
+for line in s1.splitlines():
+    gate, value = line.split(": ")
+    states[gate] = int(value)
+
+gates = []
+out_to_index = {}
+xors = {}
+zz = []
+for i, line in enumerate(s2.splitlines()):
+    o1, op, o2, _, out = line.split()
+    o1, o2 = sorted([o1, o2])
+    gate = [o1, op, o2, "->", out]
+    gates.append(gate)
+    out_to_index[out] = i
+    if out.startswith("z"):
+        zz.append(out)
+    if op == "XOR" and o1.startswith("x"):
+        (index,) = ints(o1)
+        xors[index] = gate
+
+p1 = run(states, gates)
+print(p1)
+
+NUMBER_Z_GATES = ints(sorted(zz)[-1])[0] + 1
+# print(NUMBER_Z_GATES)
+# pprint(xors)
+
+xx = [f"x{i:02}" for i in range(NUMBER_Z_GATES - 1)]
+yy = [f"y{i:02}" for i in range(NUMBER_Z_GATES - 1)]
+
+# def resolve(x):
+#     if x in xx or x in yy:
+#         return f"{x}"
+#         # return x
+#     a, op, b = gate_to_in[x]
+#     aa = resolve(a)
+#     bb = resolve(b)
+#     # print(aa, bb)
+#     aa, bb = sorted([aa, bb], reverse=True)
+#     op = "^" if op == "XOR" else ("|" if op == "OR" else "&")
+#     return f"({aa} {op} {bb})"
+#     # return [aa, op, bb]
+
+
+def find_xor(index):
+    xor = xors[index][OUT]
+    for gate in gates:
+        if gate[OP] == "XOR" and (gate[LHS] == xor or gate[RHS] == xor):
+            return gate
+    return None
+
+
+corrected = []
+for i in range(NUMBER_Z_GATES):
+    sx, sy, sz = [f"{c}{i:02}" for c in "xyz"]
+    gate = gates[out_to_index[sz]]
+    if i == 0:
+        assert gate == xors[i]
+    elif i == NUMBER_Z_GATES - 1:
+        pass  # last gate needs special check
+    else:
+        fixed = False
+        xor = xors[i]
+        if gate[OP] != "XOR":
+            cgate = find_xor(i)
+            assert cgate is not None
+            gate[OUT], cgate[OUT] = cgate[OUT], gate[OUT]
+            corrected.append(gate[OUT])
+            corrected.append(cgate[OUT])
+            out_to_index[gate[OUT]], out_to_index[cgate[OUT]] = (
+                out_to_index[cgate[OUT]],
+                out_to_index[gate[OUT]],
+            )
+            fixed = True
+            # print(f"[swap] {gate} <-> {cgate}")
+            gate = gates[out_to_index[sz]]
+        assert gate[OP] == "XOR"
+
+        # print(gate)
+        i_lhs, i_rhs = out_to_index[gate[LHS]], out_to_index[gate[RHS]]
+        a, b = gates[i_lhs], gates[i_rhs]
+
+        if a == xor:
+            # print(f"[ok] {sz} ({fixed})")
+            pass
+        elif b == xor:
+            # print(f"[ok] {sz} ({fixed})")
+            gate[0], gate[2] = gate[2], gate[0]
+        else:
+            if a[OP] == "AND":
+                a[OUT], xor[OUT] = xor[OUT], a[OUT]
+                corrected.append(a[OUT])
+                corrected.append(xor[OUT])
+                # print(f"[swap] {a} <-> {xor}")
+                out_to_index[a[OUT]], out_to_index[xor[OUT]] = (
+                    out_to_index[xor[OUT]],
+                    out_to_index[a[OUT]],
+                )
+                # print(f"[ok] {sz} (manual fix)")
+            else:
+                print(f"[nok] {sz} (don't know how to fix)")
+
+print(",".join(sorted(corrected)))
diff --git a/README.md b/README.md
index 2280fd9..f63187d 100644
--- a/README.md
+++ b/README.md
@@ -314,5 +314,6 @@ and focus. Of course, learning more algorithms and techniques helps.
 - Day 21: `00:48:40   215      0          -      -      -`
 - Day 22: `00:13:04  1930      0   00:28:29    739      0`
 - Day 23: `   >24h  20096      0       >24h  17620      0`
-- Day 24:
-- Day 25:
+- Day 24: `15:57:01 17307      0       >24h  11326      0`
+- Day 25: `10:41:54 14140      0          -      -      -`
+