From 91f700efa457a0480d4f320565678b6752b3a3ac Mon Sep 17 00:00:00 2001
From: Lachlan Meyer <lachlanmeyer@gmail.com>
Date: Thu, 26 Dec 2024 15:32:59 +1100
Subject: [PATCH] 24-2

---
 2024/24/24-2.py | 80 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 2024/24/24-2.py

diff --git a/2024/24/24-2.py b/2024/24/24-2.py
new file mode 100644
index 0000000..f14ae61
--- /dev/null
+++ b/2024/24/24-2.py
@@ -0,0 +1,80 @@
+import functools
+
+codeValues = {}
+sequences = {}
+
+def runSequence(code):
+    sequence = sequences[code]
+
+    match sequence[1]:
+        case 'AND':
+            codeValues[code] = getValue(sequence[0]) and getValue(sequence[2])
+        case 'OR':
+            codeValues[code] = getValue(sequence[0]) or getValue(sequence[2])
+        case 'XOR':
+            codeValues[code] = getValue(sequence[0]) ^ getValue(sequence[2])
+
+    return codeValues[code]
+
+@functools.cache
+def getValue(code):
+    if code in codeValues:
+        return codeValues[code]
+    
+    return runSequence(code)
+
+with open('2024/24/input.txt') as f:
+    for line in f:
+        line = line.strip()
+
+        if '->' in line:
+            split = line.split(' -> ')
+            result = split[1]
+            sequence = tuple(split[0].split(' '))
+            sequences[result] = sequence
+
+        elif ':' in line:
+            split = line.split(': ')
+            code = split[0]
+            value = int(split[1])
+            codeValues[code] = value
+
+
+# Rather than brute force a solution, I've noticed on paper that there's a consistent pattern:
+# zXX are always made up of a XOR b - except for maybe the last one (my z45 is OR but seems okay)
+# All XORs should have either xXX or yXX as input, or zXX as output like above
+# All ANDs should not lead into XORs
+# All ORs should be the output of AND, except for x00/y00
+# Appears to be a full adder, not sure if that's necessarily true, just looks it on paper
+
+# Find the gates that don't fulfull the criteria above
+badGates = []
+for code in sequences:
+    gate1, operation, gate2 = sequences[code]
+
+    if operation == 'XOR' and all(prefix not in 'xyz' for prefix in (code[0], gate1[0], gate2[0])):
+        badGates.append(code)
+    if code[0] == 'z':
+        if operation != 'XOR':
+            badGates.append(code)
+    if operation == 'XOR':        
+        if 'x00' not in (gate1, gate2):
+            if not (gate1[0] in ['x', 'y'] and gate2[0] in ['x', 'y']):
+                gate1Operation = sequences[gate1][1]
+                gate2Operation = sequences[gate2][1]
+
+                # if gate1Operation == 'AND':
+                #     badGates.append(gate1)
+                if gate2Operation == 'AND':
+                    badGates.append(gate2)
+    if operation == 'OR':
+        if 'x00' not in (gate1, gate2):
+            gate1Operation = sequences[gate1][1]
+            gate2Operation = sequences[gate2][1]
+
+            if gate1Operation == 'XOR':
+                badGates.append(gate1)
+            elif gate2Operation == 'XOR':
+                badGates.append(gate2)
+
+print(','.join(sorted(dict.fromkeys(badGates))[:-1])) #drop zXX's most significant bit
\ No newline at end of file