commit ba009e5ea9f0a5e3e7b50ab4f27b0dd17a7b2429
parent e1d5368d5edac77d26bbbc1ffd9cfc9c193a1c69
Author: Natasha Kerensikova <natgh@instinctive.eu>
Date: Sun, 15 Dec 2024 19:10:06 +0000
Day 15 references and solutions
Diffstat:
3 files changed, 201 insertions(+), 0 deletions(-)
diff --git a/2024/day15.nim b/2024/day15.nim
@@ -0,0 +1,170 @@
+# Copyright (c) 2024, Natacha Porté
+#
+# Permission to use, copy, modify, and distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+from std/math import gcd
+from std/sequtils import map, mapIt, toSeq
+from std/strutils import find, join, replace
+
+# Read input file
+
+type
+ Point = tuple
+ x, y: int
+ Input_Data = tuple
+ map: seq[string]
+ start: Point
+ moves: string
+
+func `+`(a, b: Point): Point = (x: a.x + b.x, y: a.y + b.y)
+proc `+=`(a: var Point, b: Point): void = a = a + b
+func `-`(a, b: Point): Point = (x: a.x - b.x, y: a.y - b.y)
+func `[]`(m: seq[string], p: Point): char = m[p.y][p.x]
+proc `[]=`(m: var seq[string], p: Point, c: char): void = m[p.y][p.x] = c
+
+func process_data(data: seq[string]): Input_Data =
+ var
+ in_map = true
+ has_start = false
+ moves: seq[string]
+ for s in data:
+ if s == "":
+ assert in_map
+ in_map = false
+ elif in_map:
+ let sx = s.find('@')
+ if sx >= 0:
+ assert not has_start
+ result.start = (x: sx, y: len(result.map))
+ has_start = true
+ result.map.add(s)
+ else:
+ moves.add(s)
+ assert not in_map
+ assert has_start
+ result.moves = moves.join()
+
+let
+ data = process_data(stdin.lines().toSeq())
+
+# Puzzle 1
+
+func find_robot(m: seq[string]): Point =
+ for y in 0 ..< len(m):
+ let sx = m[y].find('@')
+ if sx > 0:
+ return (x: sx, y: y)
+ assert false
+
+func direction(c: char): Point =
+ case c
+ of '<':
+ return (x: -1, y: 0)
+ of '>':
+ return (x: 1, y: 0)
+ of 'v':
+ return (x: 0, y: 1)
+ of '^':
+ return (x: 0, y: -1)
+ else:
+ assert false
+
+func valid(p: Point, m: seq[string]): bool =
+ p.x >= 0 and p.y >= 0 and p.y < len(m) and p.x < len(m[p.y])
+
+func move1(m: seq[string], c: char): seq[string] =
+ let
+ d = direction(c)
+ start = find_robot(m)
+ result = m
+ var dest = start + d
+ while valid(dest, m) and m[dest] == 'O':
+ dest += d
+ if valid(dest, m) and m[dest] == '.':
+ result[dest] = result[dest - d]
+ result[start + d] = result[start]
+ result[start] = '.'
+ else:
+ return m
+
+proc display(m: seq[string]): void =
+ for s in m:
+ echo s
+
+proc moves1(map: seq[string], moves: string): seq[string] =
+ result = map
+ for c in moves:
+ result = move1(result, c)
+# display(result)
+
+func answer(m: seq[string]): int =
+ result = 0
+ for y in 0 ..< len(m):
+ for x in 0 ..< len(m[y]):
+ if m[y][x] == 'O' or m[y][x] == '[':
+ result += 100 * y + x
+
+echo "Puzzle 1: ", answer(moves1(data.map, data.moves))
+
+# Puzzle 2
+
+let
+ map2 = data.map.mapIt(it.replace("#", "##").replace("O", "[]").replace(".", "..").replace("@", "@."))
+
+func move2(m: seq[string], c: char): seq[string] =
+ let
+ d = direction(c)
+ start = find_robot(m)
+ result = m
+ result[start] = '.'
+
+ if d.y == 0:
+ var pos = start + d
+ while valid(pos, m) and (m[pos] == '[' or m[pos] == ']'):
+ result[pos] = m[pos - d]
+ pos += d
+ if valid(pos, m) and m[pos] == '.':
+ result[pos] = m[pos - d]
+ else:
+ return m
+ else:
+ var pos = @[start + d]
+ while len(pos) > 0:
+ var next: seq[Point]
+ for p in pos:
+ case m[p]
+ of '[':
+ next.add(p + d)
+ next.add(p + d + (x: 1, y: 0))
+ of ']':
+ next.add(p + d)
+ next.add(p + d + (x: -1, y: 0))
+ of '.':
+ discard nil
+ else:
+ return m
+ for p in next:
+ result[p - d] = '.'
+ for p in pos:
+ result[p] = m[p - d]
+ pos = next
+
+proc moves2(map: seq[string], moves: string): seq[string] =
+ result = map
+ for c in moves:
+ result = move2(result, c)
+# echo c
+# display(result)
+# display(result)
+
+echo "Puzzle 2: ", answer(moves2(map2, data.moves))
diff --git a/2024/ref/day15a.txt b/2024/ref/day15a.txt
@@ -0,0 +1,10 @@
+########
+#..O.O.#
+##@.O..#
+#...O..#
+#.#.O..#
+#...O..#
+#......#
+########
+
+<^^>>>vv<v>>v<<
diff --git a/2024/ref/day15b.txt b/2024/ref/day15b.txt
@@ -0,0 +1,21 @@
+##########
+#..O..O.O#
+#......O.#
+#.OO..O.O#
+#..O@..O.#
+#O#..O...#
+#O..O..O.#
+#.OO.O.OO#
+#....O...#
+##########
+
+<vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^
+vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v
+><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv<
+<<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^
+^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^><
+^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^
+>^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^
+<><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<>
+^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v>
+v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^
