y2024d18

test.py

@@ -0,0 +1,26 @@
+# JS sucks
+for line in open('./y2024/resources/17_input.txt'):
+    if line.startswith('Program:'):
+        instructions = list(map(int, line.split(': ')[1].split(',')))
+
+def outFromA(a):
+    interim = (a % 8) ^ 3
+    c = a // (2 ** interim)
+    postC = c ^ 6
+    return (postC ^ (a % 8)) % 8
+
+candidates = [0]
+for i in range(len(instructions) - 1, -1, -1):
+    newCandidates = []
+    # print(f'Instruction: {instructions[i]}, candidates: {candidates}')
+    for c in candidates:
+        for j in range(8):
+            num = (c << 3) + j
+            out = outFromA(num)
+            # print(f'Num: {num}, Out: {out}, Instruction: {instructions[i]}')
+            if out == instructions[i]:
+                newCandidates.append(num)
+    candidates = newCandidates
+
+# print(candidates)
+print(min(candidates))