commit a717a4d451ab79253b1f501247cfccc7756adb0a
parent ef3b58cb5b357dae05a05cc6964d55f6ffbb2cb8
Author: Natasha Kerensikova <natgh@instinctive.eu>
Date: Wed, 4 Dec 2024 20:35:37 +0000
Day 4 reference and solutions
Diffstat:
4 files changed, 105 insertions(+), 0 deletions(-)
diff --git a/2024/day04.nim b/2024/day04.nim
@@ -0,0 +1,80 @@
+# 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/sequtils import toSeq
+
+# Read input file
+
+let data = stdin.lines().toSeq()
+let nlines = len(data)
+let ncols = len(data[0])
+
+# Puzzle 1
+
+proc isXmas(x, y, dx, dy: int): bool =
+ x + 3*dx >= 0 and
+ x + 3*dx < ncols and
+ y + 3*dy >= 0 and
+ y + 3*dy < ncols and
+ data[y][x] == 'X' and
+ data[y+dy][x+dx] == 'M' and
+ data[y+2*dy][x+2*dx] == 'A' and
+ data[y+3*dy][x+3*dx] == 'S'
+
+const dirs = @[(1,0), (1,1), (0,1), (-1,1), (-1,0), (-1,-1), (0,-1), (1, -1)]
+
+proc countXmasAt(x, y: int): int =
+ result = 0
+ if data[y][x] == 'X':
+ for d in dirs:
+ if isXmas(x, y, d[0], d[1]):
+ result += 1
+
+proc countXmas(): int =
+ result = 0
+ for y in 0 ..< nlines:
+ for x in 0 ..< ncols:
+ result += countXmasAt(x, y)
+
+echo "Puzzle 1: ", countXmas()
+
+# Puzzle 2
+
+const dirs2 = @[(1,1), (-1,1), (-1,-1), (1,-1)]
+
+proc isMas(x, y, dx, dy: int): bool =
+ data[y-dy][x-dx] == 'M' and
+ data[y+dy][x+dx] == 'S'
+
+proc is2Mas(x, y, i: int): bool =
+ let
+ i2 = (i + 1) mod len(dirs2)
+ d1 = dirs2[i]
+ d2 = dirs2[i2]
+ result = isMas(x, y, d1[0], d1[1]) and isMas(x, y, d2[0], d2[1])
+
+proc countMasAt(x, y: int): int =
+ result = 0
+ if data[y][x] == 'A':
+ for i in 0 ..< len(dirs2):
+ if is2Mas(x, y, i):
+ result += 1
+
+proc countMas(): int =
+ result = 0
+ for y in 1 .. nlines-2:
+ for x in 1 .. ncols-2:
+ result += countMasAt(x, y)
+
+echo "Puzzle 2: ", countMas()
diff --git a/2024/ref/day04a.txt b/2024/ref/day04a.txt
@@ -0,0 +1,5 @@
+..X...
+.SAMX.
+.A..A.
+XMAS.S
+.X....
diff --git a/2024/ref/day04b.txt b/2024/ref/day04b.txt
@@ -0,0 +1,10 @@
+MMMSXXMASM
+MSAMXMSMSA
+AMXSXMAAMM
+MSAMASMSMX
+XMASAMXAMM
+XXAMMXXAMA
+SMSMSASXSS
+SAXAMASAAA
+MAMMMXMMMM
+MXMXAXMASX
diff --git a/2024/ref/day04c.txt b/2024/ref/day04c.txt
@@ -0,0 +1,10 @@
+.M.S......
+..A..MSMS.
+.M.S.MAA..
+..A.ASMSM.
+.M.S.M....
+..........
+S.S.S.S.S.
+.A.A.A.A..
+M.M.M.M.M.
+..........
