Solve 2018 day 12

2018/d12.py

@@ -1,53 +1,12 @@
-from lib import *
+def score(state, offset):
-
+    r = 0
-data = """initial state: #..#.#..##......###...###
+    for i in range(len(state)):
-
+        if state[i] == "#":
-...## => #
+            r += i + offset
-..#.. => #
+    return r
-.#... => #
-.#.#. => #
-.#.## => #
-.##.. => #
-.#### => #
-#.#.# => #
-#.### => #
-##.#. => #
-##.## => #
-###.. => #
-###.# => #
-####. => #"""
 
 
-all = """
+def solve(data, target_i):
-    
-
-                 1         2         3     
-       0         0         0         0     
- 0: ...#..#.#..##......###...###...........
- 1: ...#...#....#.....#..#..#..#...........
- 2: ...##..##...##....#..#..#..##..........
- 3: ..#.#...#..#.#....#..#..#...#..........
- 4: ...#.#..#...#.#...#..#..##..##.........
- 5: ....#...##...#.#..#..#...#...#.........
- 6: ....##.#.#....#...#..##..##..##........
- 7: ...#..###.#...##..#...#...#...#........
- 8: ...#....##.#.#.#..##..##..##..##.......
- 9: ...##..#..#####....#...#...#...#.......
-10: ..#.#..#...#.##....##..##..##..##......
-11: ...#...##...#.#...#.#...#...#...#......
-12: ...##.#.#....#.#...#.#..##..##..##.....
-13: ..#..###.#....#.#...#....#...#...#.....
-14: ..#....##.#....#.#..##...##..##..##....
-15: ..##..#..#.#....#....#..#.#...#...#....
-16: .#.#..#...#.#...##...#...#.#..##..##...
-17: ..#...##...#.#.#.#...##...#....#...#...
-18: ..##.#.#....#####.#.#.#...##...##..##..
-19: .#..###.#..#.#.#######.#.#.#..#.#...#..
-20: .#....##....#####...#######....#.#..##.
-    """
-
-
-def part_1(data):
     state = None
     map = {}
     for line in data.splitlines():
@@ -60,72 +19,41 @@ def part_1(data):
             map[lhs] = rhs
 
     assert state is not None
-    offset = 50
+    seen = {}
-    state = "." * offset + state + "." * offset
+    offset = 0
-    for i in range(20):
+    for i in range(target_i):
-        ns = ".."
+        while not state.startswith("...."):
+            state = "." + state
+            offset -= 1
+        while not state.endswith("...."):
+            state += "."
+
+        if state in seen:
+            prev_i, prev_score = seen[state]
+            assert (i - prev_i) == 1
+            current_score = score(state, offset)
+            delta_score = current_score - prev_score
+            final_score = current_score + (target_i - i) * delta_score
+            print(final_score)
+            return
+        else:
+            seen[state] = (i, score(state, offset))
+
+        ns = ""
         for i in range(2, len(state) - 2):
-            s = state[i - 2:i + 3]
+            s = state[i - 2 : i + 3]
             ns += map[s]
-        ns += ".."
         state = ns
-
+        offset += 2
-    r = 0
+    print(score(state, offset))
-    for i in range(2, len(state) - 2):
-        if state[i] == "#":
-            r += (i - offset)
-    print(r)
-
-
-def part_2(data):
-    state = None
-    map = {}
-    for line in data.splitlines():
-        if "initial state" in line:
-            _, rest = line.split(":")
-            state = rest.strip()
-        if "=>" in line:
-            lhs, rhs = line.split(" => ")
-            assert lhs not in map
-            map[lhs] = rhs
-
-    assert state is not None
-    offset = 55
-    state = "." * offset + state + offset * ".."
-    for i in range(100):
-        # if state.startswith("..."):
-        #     assert False
-        # elif state.startswith("..#"):
-        #     pass
-        # elif state.startswith(".#"):
-        #     state = "." + state
-        #     offset += 1
-        # elif state.startswith("#"):
-        #     state = ".." + state
-        #     offset += 2
-        print(state)
-
-        ns = ".."
-        for i in range(2, len(state) - 2):
-            s = state[i - 2:i + 3]
-            ns += map[s]
-        ns += ".."
-        state = ns
-        # print(state)
-
-    r = 0
-    for i in range(2, len(state) - 2):
-        if state[i] == "#":
-            r += (i - offset)
-    print(r)
 
 
 def main():
     input_file = __file__.replace(".py", ".txt")
     with open(input_file) as f:
         data = f.read()
-    part_1(data)
+    solve(data, 20)
-    part_2(data)
+    solve(data, 50 * 10**9)
 
 
 if __name__ == "__main__":

README.md

@@ -100,7 +100,8 @@ written in Python.
 - Day 9: 1:17:52
 - Day 10: 19:14
 - Day 11: 22:52
-- Day 12:
+- Day 12: 180:00
+- Day 13:
 
 
 # 2022