Solve 2016:17 p1-2 "Two Steps Forward"

Generators baby.

2016-python2/output/__init__.py

@@ -30,28 +30,6 @@ ADJ = [
 ]
 
 
-def answer(part_index, fmt_string):
-    """Decorator to present a solution in a human readable format"""
-
-    def decorator_aoc(func):
-        @functools.wraps(func)
-        def wrapper_aoc(*args, **kwargs):
-            decorate = kwargs.get("decorate", False)
-            if decorate:
-                del kwargs["decorate"]
-            answer = func(*args, **kwargs)
-            if not decorate:
-                print(answer)
-            else:
-                formatted = fmt_string.format(answer)
-                print(f" {part_index}) {formatted}")
-            return answer
-
-        return wrapper_aoc
-
-    return decorator_aoc
-
-
 def ints(s):
     """Extract all integers from a string"""
     return [int(n) for n in re.findall(r"\d+", s)]

2016-python2/output/day_17.py

@@ -0,0 +1,41 @@
+from collections import deque
+from hashlib import md5
+
+from output import DD
+
+
+def solve(data):
+    paths = list(bfs(data))
+    p1 = "".join(paths[0])
+    p2 = len(paths[-1])
+    return p1, p2
+
+
+def bfs(code):
+    q = deque([((0, 0), [])])
+    T = (3, 3)
+    K = "UDLR"
+    while q:
+        m, d = q.popleft()
+        U, D, L, R, *_ = md5((code + "".join(d)).encode()).hexdigest()
+        y, x = m
+        for udlr in [K[k] for k, n in enumerate([U, D, L, R]) if isopen(n)]:
+            dy, dx = DD[udlr]
+            if (y + dy, x + dx) == T:
+                yield d + [udlr]
+            elif 0 <= y + dy < 4 and 0 <= x + dx < 4:
+                q.append(((y + dy, x + dx), d + [udlr]))
+
+
+def isopen(c):
+    return c in "bcdef"
+
+
+if __name__ == "__main__":
+    with open("./input/17.txt", "r") as f:
+        inp = f.read().strip()
+
+    p1, p2 = solve(inp)
+
+    print(p1)
+    print(p2)