Solve day 12.

README.md

@@ -10,5 +10,5 @@
 - Day 8: 25:00; I was doing pretty decent here.
 - Day 9: 57:00; my input parse function did not consider negative values...
 - Day 10: 180:00; this one was hard for me.
-- Day 11: 68:00; okay but not elegant and way too slow ofc.
-- Day 12: 
+- Day 11: 68:00; okay but not elegant and way too slow ofc; x-ray solution would have been neat
+- Day 12: 52:00 and 22:00 for leaderboard; had the right idea and I am good at this type of problem

d12.py

@@ -1,43 +1,69 @@
 import lib
+from functools import lru_cache
 
 EXAMPLE = """
+???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1
 """
 
-def solve(lines: list[str]):
+@lru_cache
+def count(elems, groups):
+    if not elems and not groups:
+        return 1
+    elif elems and not groups:
+        if all(e in ['.', '?'] for e in elems):
+            return 1
+        return 0
+    elif not elems and groups:
+        return 0
+
+    r = 0
+    if elems[0] in ['?', '.']:
+        r += count(elems[1:], groups)
+
+    g = groups[0]
+    if len(elems) < g:
+        return 0
+
+    es, rest = elems[:g], elems[g:]
+    if all(e in ['?', '#'] for e in es) and (len(rest) == 0 or rest[0] in ['.', '?']):
+        r += count(rest[1:], groups[1:])
+    return r
+
+
+def solve(lines: list[str], repeat=1):
+    all = []
+    for (_, line) in enumerate(lines):
+        springs, numbers = line.split()
+        numbers = tuple(lib.str_to_int_list(numbers))
+        ns = "?".join([springs for _ in range(repeat)])
+        all.append((tuple(ns), numbers * repeat))
+
     res = 0
-
-    # g = list(map(list, lines))
-    # for (ri, r) in enumerate(g):
-    #     for (ci, c) in enumerate(r):
-    #         pass
-
-    for (i, line) in enumerate(lines):
-        print(i, line)
-        # digits = lib.str_to_int_list(line)
-        # digit = lib.str_to_single_int(line)
+    for a in all:
+        # print(a, count(*a))
+        res += count(*a)
+    # 28:00
+    # 50:00 total
     return res
 
-def solve2(lines: list[str]):
-    res = 0
-    for (i, line) in enumerate(lines):
-        print(i, line)
-    return res
 
 def main():
     lines = lib.str_to_lines_no_empty(EXAMPLE)
     print("Example  1:", solve(lines))
-    return
 
     lines = lib.str_to_lines_no_empty(open("i12.txt").read())
     print("Solution 1:", solve(lines))
-    return
 
     lines = lib.str_to_lines_no_empty(EXAMPLE)
-    print("Example  2:", solve2(lines))
-    return
+    print("Example  2:", solve(lines, 5))
 
     lines = lib.str_to_lines_no_empty(open("i12.txt").read())
-    print("Solution 2:", solve2(lines))
+    print("Solution 2:", solve(lines, 5))
 
 if __name__ == "__main__":
     main()