Solve 2025 day 7

.gitignore

@@ -4,6 +4,8 @@
 __pycache__/
 *.py[cod]
 *$py.class
+.python-version
+uv.lock
 
 # C extensions
 *.so

2025/d03.py

@@ -0,0 +1,34 @@
+from lib import get_data
+
+data = get_data(__file__)
+
+
+def max_joltage(xs: str, target_len: int) -> int:
+    def dynamic(xs: str) -> dict[int, str]:
+        if len(xs) == 0:
+            return {0: ""}
+
+        rs = dynamic(xs[1:])
+        for i in range(target_len, 0, -1):
+            if not (i - 1) in rs:
+                continue
+            nv = int(xs[0] + rs[i - 1])
+            if not i in rs:
+                rs[i] = str(nv)
+            elif nv > int(rs[i]):
+                rs[i] = str(nv)
+        return rs
+
+    rs = dynamic(xs)
+    return int(rs[target_len])
+
+
+r1 = 0
+r2 = 0
+for line in data.splitlines():
+    r1 += max_joltage(line, 2)
+    r2 += max_joltage(line, 12)
+
+
+print(r1)
+print(r2)

2025/d04.py

@@ -0,0 +1,32 @@
+from lib import get_data, Grid2D
+
+data = get_data(__file__)
+g = Grid2D(data)
+
+r = 0
+adjs = []
+for pos in g.all_coords():
+    if g[pos] != "@":
+        continue
+    nr_of_rolls_adj = len([nb for nb in g.neighbors_adj(pos) if g[nb] == "@"])
+    if nr_of_rolls_adj < 4:
+        r += 1
+        adjs.append(pos)
+print(r)
+
+r = 0
+while True:
+    adjs = []
+    for pos in g.all_coords():
+        if g[pos] != "@":
+            continue
+        nr_of_rolls_adj = len([nb for nb in g.neighbors_adj(pos) if g[nb] == "@"])
+        if nr_of_rolls_adj < 4:
+            adjs.append(pos)
+    if adjs:
+        r += len(adjs)
+        for a in adjs:
+            g[a] = "."
+    else:
+        break
+print(r)

2025/d05.py

@@ -0,0 +1,45 @@
+from lib import get_data
+
+data = get_data(__file__)
+
+ranges, ids = data.split("\n\n")
+ids = tuple(map(int, ids.splitlines()))
+ranges = [list(map(int, line.split("-"))) for line in ranges.splitlines()]
+
+updated = True
+while updated:
+    updated = False
+    sorted_ranges = []
+    for lo, up in ranges:
+        assert lo <= up
+        for i in range(len(sorted_ranges)):
+            slo, sup = sorted_ranges[i]
+            if up + 1 < slo:
+                sorted_ranges.insert(i, (lo, up))
+            elif lo < slo:
+                sorted_ranges[i] = (lo, max(up, sup))
+                updated = True
+            elif lo <= sup:
+                sorted_ranges[i] = (slo, max(up, sup))
+                updated = True
+            else:
+                continue
+            break
+        else:
+            sorted_ranges.append((lo, up))
+    ranges = sorted_ranges
+
+
+result_part_1 = 0
+for id_to_check in ids:
+    for lo, up in ranges:
+        if lo <= id_to_check <= up:
+            result_part_1 += 1
+            break
+print(result_part_1)
+
+result_part_2 = 0
+for lo, up in ranges:
+    result_part_2 += up - lo + 1
+print(result_part_2)
+assert result_part_2 == 350780324308385

2025/d06.py

@@ -0,0 +1,60 @@
+from lib import get_data
+from typing import TypeVar
+
+T = TypeVar('T')
+
+data = """123 328  51 64 
+ 45 64  387 23 
+  6 98  215 314
+*   +   *   +  """
+data = get_data(__file__)
+
+def mul(xs):
+    r = 1
+    for x in xs:
+        r *= x
+    return r
+
+lines = zip(*[line.split() for line in data.splitlines()])
+
+r = 0
+for xs in lines:
+    xs, op = xs[:-1], xs[-1]
+    xs = list(map(int, xs))
+    if op == "+":
+        r += sum(xs)
+    elif op == "*":
+        r += mul(xs)
+    else:
+        assert False, "Unexpected op"
+print(r)
+
+def split(xs: list[T], delim: T) -> list[list[T]]:
+    res = [[]]
+    for x in xs:
+        if x == delim:
+            res.append([])
+        else:
+            res[-1].append(x)
+    return res
+
+chars_trans: list[tuple[str]]  = list(zip(*[line for line in data.splitlines()]))
+lines_trans: list[str] = list(map(lambda line: "".join(line).strip(), chars_trans))
+cols: list[list[str]] = split(lines_trans, '')
+
+r2 = 0
+for xs in cols:
+    x0 = xs[0]
+    acc, op = int(x0[:-1]), x0[-1]
+    for x in xs[1:]:
+        x = int(x)
+        if op == "+":
+            acc += x
+        elif op == "*":
+            acc *= x
+        else:
+            assert False, "Unexpected op"
+    r2 += acc
+
+print(r2)
+

2025/d07.py

@@ -0,0 +1,59 @@
+from lib import get_data, Grid2D
+from collections import defaultdict
+
+
+data = """.......S.......
+...............
+.......^.......
+...............
+......^.^......
+...............
+.....^.^.^.....
+...............
+....^.^...^....
+...............
+...^.^...^.^...
+...............
+..^...^.....^..
+...............
+.^.^.^.^.^...^.
+..............."""
+data = get_data(__file__)
+
+g = Grid2D(data)
+beams = [g.find('S')[0][1]]
+
+splits = 0
+for row in range(1, g.n_rows - 1):
+    new_beams = set()
+    for beam in beams:
+        field = g[(row, beam)]
+        if field == "^":
+            splits += 1
+            new_beams.add(beam - 1)
+            new_beams.add(beam + 1)
+        elif field == ".":
+            new_beams.add(beam)
+        else:
+            assert False, "unexpected field"
+    beams = list(new_beams)
+    # print(beams)
+
+print(splits)
+
+beams = {g.find('S')[0][1]: 1}
+for row in range(1, g.n_rows - 1):
+    new_beams = defaultdict(int)
+    for beam, count in beams.items():
+        field = g[(row, beam)]
+        if field == "^":
+            new_beams[beam - 1] += count
+            new_beams[beam + 1] += count
+        elif field == ".":
+            new_beams[beam] += count
+        else:
+            assert False, "unexpected field"
+    beams = new_beams
+
+print(sum(beams.values()))
+

README.md

@@ -12,7 +12,21 @@ stressful and this will actually be more fun. Thank you Eric Wastl and let's go!
   ticks naively. Maybe I should revisit this.
 - Day 2: The simple direct approach with iterating over all the IDs in the
   ranges just worked okay. Not pretty but acceptable.
-- Day 3:
+- Day 3: Fun dynamic programming problem. Part 2 took me a little too long
+  overall but it was fun.
+- Day 4: One of the easier grid based puzzles. Less than five minutes with
+  existing grid library.
+- Day 5: A problem with ranges; I decided to implement proper range merging this
+  time because I always kind of avoid that. I could probably decrease the
+  complexity from O(n^2) to O(n log(n)) but I am happy that I've implemented
+  merging at all.
+- Day 6: Transposing some rows and cols. Fun and good to keep the brain fit
+  but not really hard. I would have been way too slow for the leaderboard
+  in pre-AI years.
+- Day 7: Grid puzzle that required non-naiv implementation for part 2. Took
+  me a second to realize that I could not save the coordinates by list but
+  had to use a count to be efficient.
+- Day 8:
 
 
 ## AoC 2024

pyproject.toml

@@ -0,0 +1,10 @@
+[project]
+name = "aocpy"
+version = "0.1.0"
+description = "Make ruff and ty available via uv"
+readme = "README.md"
+requires-python = ">=3.13"
+dependencies = [
+    "ruff>=0.14.11",
+    "ty>=0.0.11",
+]