2 files changed, 26 insertions(+), 1 deletions(-)

M 2020/day07.py
M 2020/day08.py

@@ 1,6 1,6 @@
 #!/usr/bin/env python3
 
-from typing import Dict, List, Tuple
+from typing import Dict, Tuple
 
 from aoc import Puzzle, run
 

@@ 163,6 163,31 @@ acc +6"""
 
         return vm.acc
 
+    def run_part2_bruteforce(self, data):
+        visited_ips = set()
+
+        def detect_loop(vm):
+            if vm.ip in visited_ips:
+                vm.stopped = True
+            else:
+                visited_ips.add(vm.ip)
+
+        for pos in range(len(data.ops)):
+            op, arg = data.ops[pos]
+            if op not in ("nop", "jmp"):
+                continue
+
+            vm = data.clone()
+            visited_ips.clear()
+            new_op = "jmp" if op == "nop" else "nop"
+            vm.ops[pos] = (new_op, arg)
+            vm.callback = detect_loop
+            vm.run()
+
+            if not vm.stopped:
+                # Program ran without being interrupted!
+                return vm.acc
+
 
 if __name__ == "__main__":
     run(obj=Day08())