🐶

y2022/p21.py

+from functools import lru_cache
+
+
+@lru_cache(maxsize=None)
+def fn(seed=None):
+    instructions = map(str.split, text.replace(':', '').splitlines())
+    while instructions:
+        act, *instructions = instructions
+        try:
+            match act:
+                case ['root', a, _, b] if seed is not None:
+                    return eval(a) - eval(b)
+                case ['humn', _] if seed is not None:
+                    locals()['humn'] = seed
+                case [name, a, x, b]:
+                    locals()[name] = eval(a + x + b)
+                case [name, a]:
+                    locals()[name] = eval(a)
+                case default:
+                    raise RuntimeError(default)
+        except NameError:
+            instructions.append(act)
+    return int(locals()['root'])
+
+
+def bisect(fn, x1, x2):
+    for _ in range(100):
+        xn = x1 + (x2 - x1) // 2
+        if fn(xn) == 0:
+            return xn
+        elif abs(fn(x1)) > abs(fn(x2)):
+            x1 = xn
+        else:
+            x2 = xn
+
+
+text = open(0).read()
+print(fn())
+print(bisect(fn, 0, 10_000_000_000_000))