2018 day 20 wip

2018/d20.py

@@ -0,0 +1,107 @@
+from lib import get_data, add2
+from collections import defaultdict
+
+data = "^WNE$"
+data = "^ENWWW(NEEE|SSE(EE|N))$"
+data = "^ESSWWN(E|NNENN(EESS(WNSE|)SSS|WWWSSSSE(SW|NNNE)))$"
+data = "^WSSEESWWWNW(S|NENNEEEENN(ESSSSW(NWSW|SSEN)|WSWWN(E|WWS(E|SS))))$"
+
+DIRS = {
+    "N": (-1, 0),
+    "E": (0, 1),
+    "S": (1, 0),
+    "W": (0, -1),
+}
+
+
+def part_1(data):
+    data = data[1:]
+
+    # def parse(i):
+    #     max_len = 0
+    #     cur_len = 0
+    #     while i < len(data):
+    #         c = data[i]
+    #         if c in DIRS.keys():
+    #             i += 1
+    #             cur_len += 1
+    #         elif c == "(":
+    #             sub_len, i = parse(i + 1)
+    #             cur_len += sub_len
+    #         elif c == "|":
+    #             max_len = max(max_len, cur_len)
+    #             cur_len = 0
+    #             i += 1
+    #         elif c == ")":
+    #             all_max = max(max_len, cur_len)
+    #             return all_max, i + 1
+    #         elif c == "$":
+    #             max_len = max(max_len, cur_len)
+    #             i += 1
+    #         else:
+    #             print(c)
+    #             assert False
+    #     return max_len, i
+    #
+    # print(parse(0)[0])
+
+    g = defaultdict(set)
+    def parse(xs, i):
+        xs_orig = xs.copy()
+        xs_done = []
+
+        while i < len(data):
+            c = data[i]
+            if c in DIRS.keys():
+                for xi in range(len(xs)):
+                    pos = xs[xi]
+                    npos = add2(pos, DIRS[c])
+                    g[pos].add(npos)
+                    g[npos].add(pos)
+                    xs[xi] = npos
+                i += 1
+            elif c == "(":
+                xs, i = parse(xs, i + 1)
+            elif c == "|":
+                xs_done += xs
+                xs = xs_orig
+                i += 1
+            elif c == ")":
+                xs_done += xs
+                return xs_done, i + 1
+            elif c == "$":
+                xs_done += xs
+                i += 1
+            else:
+                assert False
+        return xs_done, i
+
+    parse([(0, 0)], 0)
+
+    seen = set()
+    dists = {}
+    xs = [(0, 0)]
+    steps = 0
+    while len(xs) > 0:
+        nxs = []
+        for x in xs:
+            if x in seen:
+                continue
+            seen.add(x)
+            dists[x] = steps
+            for nb in g[x]:
+                if not nb in seen:
+                    nxs.append(nb)
+        xs = nxs
+        steps += 1
+
+    print(max(dists.values()))
+
+
+def main():
+    # data = get_data(__file__).strip()
+    part_1(data)
+
+
+if __name__ == "__main__":
+    main()