Finish 2020.

2018/d20.py

@@ -1,11 +1,6 @@
 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),
@@ -13,13 +8,19 @@ DIRS = {
     "W": (0, -1),
 }
 
-
-def part_1(data):
+data = get_data(__file__).strip()
 g = defaultdict(set)
-
+seen = set()
 stack: list[tuple[tuple, int, list]] = [((0, 0), 0, [])]
 while len(stack) > 0:
     pos, i, i_outs = stack.pop()
+
+    c = (pos, i, tuple(i_outs))
+    if c in seen:
+        continue
+    else:
+        seen.add(c)
+
     assert i is not None
     while i < len(data):
         c = data[i]
@@ -69,77 +70,18 @@ def part_1(data):
         else:
             assert False
 
-
-    # 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
+over_thousand = set()
 while len(xs) > 0:
     nxs = []
     for x in xs:
         if x in seen:
             continue
+        if steps >= 1000:
+            over_thousand.add(x)
         seen.add(x)
         dists[x] = steps
         for nb in g[x]:
@@ -149,12 +91,4 @@ def part_1(data):
     steps += 1
 
 print(max(dists.values()))
-
-
-def main():
-    # data = get_data(__file__).strip()
-    part_1(data)
-
-
-if __name__ == "__main__":
-    main()
+print(len(over_thousand))

README.md

@@ -107,7 +107,7 @@ Solutions and utility script for Advent of Code challenges in Python.
 - Day 17: 180:00
 - Day 18: 24:04
 - Day 19: days (super fun, but hard for me)
-- Day 20:
+- Day 20: weeks (a cache was all it took - weak)
 - Day 21: 28:40 (16th - brute force but still not so bad)
 - Day 22: 185:00 (should not have been so slow but was fun)
 - Day 23: days