Day 4: Ceres Search

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FAQ

  • Sparrow_1029English
    2·
    2 hours ago

    Rust

    Ugh. Spent way too long on today’s. Should have just used my own grid structure from last year. I will likely refactor to use that. Even though it’s likely a super slow implementation, the convenience of dealing with it is better than shoehorning in the grid::Grid<T> from that crate.

    solution (no supporting code) 
    use grid::Grid;

use crate::shared::{
    grid2d::{iter_diag_nesw, iter_diag_nwse, Point},
    util::read_lines,
};

fn parse_grid(input: &[String]) -> Grid<u8> {
    let cols = input.first().unwrap().len();
    Grid::from_vec(
        input
            .iter()
            .flat_map(|row| row.chars().map(|c| c as u8).collect::<Vec<u8>>())
            .collect(),
        cols,
    )
}

fn part1(grid: &Grid<u8>) -> usize {
    let mut xmas_count = 0;
    let rows = grid
        .iter_rows()
        .map(|d| String::from_utf8(d.copied().collect()).unwrap());
    let cols = grid
        .iter_cols()
        .map(|d| String::from_utf8(d.copied().collect()).unwrap());
    for diag in iter_diag_nesw(grid)
        .chain(iter_diag_nwse(grid))
        .filter_map(|d| {
            if d.len() >= 4 {
                Some(String::from_utf8(d.clone()).unwrap())
            } else {
                None
            }
        })
        .chain(rows)
        .chain(cols)
    {
        xmas_count += diag.matches("XMAS").count() + diag.matches("SAMX").count()
    }
    xmas_count
}

fn part2(grid: &Grid<u8>) -> usize {
    let mut xmas_count = 0;
    let valid = [
        [b'M', b'M', b'S', b'S'],
        [b'M', b'S', b'S', b'M'],
        [b'S', b'M', b'M', b'S'],
        [b'S', b'S', b'M', b'M'],
    ];
    for x in 1..grid.cols() - 1 {
        for y in 1..grid.rows() - 1 {
            if grid.get(y, x) == Some(&b'A')
                && valid.contains(
                    &(Point::new(x as isize, y as isize)
                        .diagonal_neighbors(grid)
                        .map(|i| i.unwrap_or(0))),
                )
            {
                xmas_count += 1;
            }
        }
    }
    xmas_count
}

pub fn solve() {
    let input = read_lines("inputs/day04.txt");
    let grid = parse_grid(&input);
    println!("Part 1: {}", part1(&grid));
    println!("Part 2: {}", part2(&grid));
}

    And here’s a link to the Github if you care to see the gross supporting code :D

  • Karmmah@lemmy.world
    1·
    4 hours ago

    Julia

    Had some time to clean up the code today since the solution was quite straight forward after making a plan on how to approach it.

    spoiler 
    function readWordSearch(inputFile::String)::Matrix{Char}
	f = open(inputFile,"r")
	lines::Vector{String} = readlines(f)
	close(f)
	wordSearch = Matrix{Char}(undef,length(lines),length(lines))
	for (i,line) in enumerate(lines)
		wordSearch[i,:] = collect(line)
	end
	return wordSearch
end

function countXMASAppearances(wS::Matrix{Char})::Int
	appearanceCount::Int = 0
	for i=1 : size(wS)[1] #lines
		for j=1 : size(wS)[2] #columns
			wS[i,j]!='X' ? continue : nothing #continue if char is not X
			#if char is X, check surrounding area
			# check horizontals
			#left
			j>=4 ? (wS[i,j-1]*wS[i,j-2]*wS[i,j-3]=="MAS" ? appearanceCount+=1 : nothing) : nothing
			#right
			j<=size(wS)[2]-3 ? (wS[i,j+1]*wS[i,j+2]*wS[i,j+3]=="MAS" ? appearanceCount+=1 : nothing) : nothing
			# check verticals
			#up
			i>=4 ? (wS[i-1,j]*wS[i-2,j]*wS[i-3,j]=="MAS" ? appearanceCount+=1 : nothing) : nothing
			#down
			i<=size(wS)[1]-3 ? (wS[i+1,j]*wS[i+2,j]*wS[i+3,j]=="MAS" ? appearanceCount+=1 : nothing) : nothing
			# check diagonals
			#left up
			i>=4 && j>=4 ? (wS[i-1,j-1]*wS[i-2,j-2]*wS[i-3,j-3]=="MAS" ? appearanceCount+=1 : nothing) : nothing
			#right up
			i>=4 && j<=size(wS)[2]-3 ? (wS[i-1,j+1]*wS[i-2,j+2]*wS[i-3,j+3]=="MAS" ? appearanceCount+=1 : nothing) : nothing
			#left down
			i<=size(wS)[1]-3 && j>=4 ? (wS[i+1,j-1]*wS[i+2,j-2]*wS[i+3,j-3]=="MAS" ? appearanceCount+=1 : nothing) : nothing
			#right down
			i<=size(wS)[1]-3 && j<=size(wS)[2]-3 ? (wS[i+1,j+1]*wS[i+2,j+2]*wS[i+3,j+3]=="MAS" ? appearanceCount+=1 : nothing) : nothing
		end
	end
	return appearanceCount
end

function countX_MASAppearances(wordSearch::Matrix{Char})::Int
	appearances::Int = 0
	for l=2 : size(wordSearch)[1]-1
		for c=2 : size(wordSearch)[2]-1
			wordSearch[l,c]!='A' ? continue : nothing
			checkArr = [wordSearch[l-1,c-1],wordSearch[l-1,c+1],wordSearch[l+1,c-1],wordSearch[l+1,c+1]]
			if checkArr in [['M','M','S','S'],['M','S','M','S'],['S','S','M','M'],['S','M','S','M']]
				appearances += 1
			end
		end
	end
	return appearances
end

wordSearch::Matrix{Char} = readWordSearch(inputFile
prinltn("part 1 appearances: $(countXMASAppearances(wordSearch))")
prinltn("part 2 appearances: $(countX_MASAppearances(wordSearch))")

  • Andy
    3·
    4 hours ago

    Factor

    spoiler 
    : get-input ( -- rows )
  "vocab:aoc-2024/04/input.txt" utf8 file-lines ;

: verticals ( rows -- lines )
  [ dimension last [0..b) ] keep cols ;

: slash-origins ( dimension -- coords )
  [ first [0..b) [ 0 2array ] map ] [
    first2 [ 1 - ] [ 1 (a..b] ] bi*
    [ 2array ] with map
  ] bi append ;

: backslash-origins ( dimension -- coords )
  first2
  [ [0..b) [ 0 2array ] map ]
  [ 1 (a..b] [ 0 swap 2array ] map ] bi* append ;

: slash ( rows origin -- line )
  first2
  [ 0 [a..b] ]
  [ pick dimension last [a..b) ] bi* zip
  swap matrix-nths ;

: backslash ( rows origin -- line )
  [ dup dimension ] dip first2
  [ over first [a..b) ]
  [ pick last [a..b) ] bi* zip nip
  swap matrix-nths ;

: slashes ( rows -- lines )
  dup dimension slash-origins
  [ slash ] with map ;

: backslashes ( rows -- lines )
  dup dimension backslash-origins
  [ backslash ] with map ;

: word-count ( word line -- n )
  dup reverse rot
  '[ _ subseq-indices length ] bi@ + ;

: part1 ( -- n )
  "XMAS" get-input
  { [ ] [ verticals ] [ slashes ] [ backslashes ] } cleave-array concat
  [ word-count ] with map-sum ;

: origin-adistances ( rows origins line-quot: ( rows origin -- line ) -- origin-adistances-assoc )
  with zip-with
  "MAS" "SAM" [ '[ [ _ subseq-indices ] map-values ] ] bi@ bi append
  harvest-values
  [ [ 1 + ] map ] map-values ; inline

: a-coords ( origin-adistances coord-quot: ( adistance -- row-delta col-delta ) -- coords )
  '[ first2 [ @ 2array v+ ] with map ] map-concat ; inline

: slash-a-coords ( rows -- coords )
  dup dimension slash-origins [ slash ] origin-adistances
  [ [ 0 swap - ] keep ] a-coords ;

: backslash-a-coords ( rows -- coords )
  dup dimension backslash-origins [ backslash ] origin-adistances
  [ dup ] a-coords ;

: part2 ( -- n )
  get-input [ slash-a-coords ] [ backslash-a-coords ] bi
  intersect length ;

    Better viewed on GitHub.

  • Tessellecta@feddit.nl
    1·
    4 hours ago

    Python

    &lt;spoiler title&gt; 
    def read_input(path):
    with open(path) as f:
        lines = f.readlines()
        for i, line in enumerate(lines):
            ln = line.replace("\n","")
            lines[i] = ln
    return lines

def find_X(lines):
    Xes = []
    for j, line in enumerate(lines):
        ind = [i for i, ltr in enumerate(line) if ltr == "X"]
        for i in ind:
            Xes.append((j,i))
    return Xes

def find_M(lines, x, dim):
    # Check for Ms
    M_dirs = []
    for i in [-1, 0, 1]:
        x_ind = x[0] + i
        if x_ind>=0 and x_ind<dim:
            for j in [-1, 0, 1]:
                y_ind = x[1]+j
                if y_ind>=0 and y_ind<dim:
                    if lines[x_ind][y_ind] == "M":
                        M = [(x_ind, y_ind), (i,j)]
                        M_dirs.append(M)
    return M_dirs

def check_surroundings(loc, lines, check_char, direction):
    max = len(lines)-1
    check_lock = [loc[i]+direction[i] for i in range(len(loc))]
    if all(i>=0 and i<=max for i in check_lock) and check_char in str(lines[check_lock[0]][check_lock[1]]):
        return True
    else:
        return False

def part_one(lines):
    ans = 0 

    X = find_X(lines)
    dim = len(lines[0])
    for x in X:
        M = find_M(lines, x, dim)
        for m in M:
            loc = m[0]
            dir = m[1]
            
            if not check_surroundings(loc, lines, 'A', dir):
                continue
            
            loc = [loc[0]+dir[0], loc[1]+dir[1]]
            if not all(i>=0 and i<=dim-1 for i in loc):
                continue
            if not check_surroundings(loc, lines, 'S', dir):
                continue
            
            ans+=1
    return ans

def extract_square(lines, loc):
    str = ""
    for i in range(-1,2,1):
        for j in range(-1,2,1):
            x_ind = loc[0]+i
            y_ind = loc[1]+j
            if not all(p>=0 and p<=len(lines[0])-1 for p in [x_ind, y_ind]):
                raise ValueError("The given lock is at the edge of the grid and therefore will not produce a square")
            str += lines[x_ind][y_ind]
    return str

def check_square(square):
    if not square[4]=="A":
        return False
    elif not ((square[0]=="M" and square[8]=="S") or (square[0]=="S" and square[8]=="M")):
        return False
    elif not ((square[2]=="M" and square[6]=="S") or (square[2]=="S" and square[6]=="M")):
        return False
    else: return True

def part_two(lines):
    ans = 0
    dim = len(lines[0])
    for i in range(1,dim-1):
        for j in range(1,dim-1):
            square = extract_square(lines, (i,j))
            if check_square(square):
                ans += 1
    return ans

path = r'Day_4\input.txt'
lines = read_input(path)
print("Answer part 1: ", part_one(lines))
print("Answer part 2: ", part_two(lines))
  • Zarlin@lemmy.world
    1·
    4 hours ago

    Nim

    import ../aoc, strutils

type
  Cell* = tuple[x,y:int]

#the 8 grid direction
const directions : array[8, Cell] = [
  (1, 0), (-1, 0),
  (0, 1), ( 0,-1),
  (1, 1), (-1,-1),
  (1,-1), (-1, 1)
]

const xmas = "XMAS"

#part 1
proc searchXMAS*(grid:seq[string], x,y:int):int =
  #search in all 8 directions (provided we can find a full match in that direction)
  let w = grid[0].len
  let h = grid.len
  
  for dir in directions:
    # check if XMAS can even fit
    let xEnd = x + dir.x * 3
    let yEnd = y + dir.y * 3
    if xEnd < 0 or xEnd >= w or
       yEnd < 0 or yEnd >= h:
      continue;
    
    #step along direction
    var matches = 0
    for s in 0..3:
      if grid[y + dir.y * s][x + dir.x * s] == xmas[s]:
        inc matches
        
    if matches == xmas.len:
      inc result

#part 2
proc isMAS(grid:seq[string], c, o:Cell):bool=
  let ca : Cell = (c.x+o.x, c.y+o.y)
  let cb : Cell = (c.x-o.x, c.y-o.y)
  let a = grid[ca.y][ca.x]
  let b = grid[cb.y][cb.x]
  (a == 'M' and b == 'S') or (a == 'S' and b == 'M')

proc searchCrossMAS*(grid:seq[string], x,y:int):bool =
  grid[y][x] == 'A' and
  grid.isMAS((x,y), (1,1)) and
  grid.isMAS((x,y), (1,-1))

proc solve*(input:string): array[2,int] =
  let grid = input.splitLines
  let w = grid[0].len
  let h = grid.len
  
  #part 1
  for y in 0..<h:
    for x in 0..<w:
      result[0] += grid.searchXMAS(x, y)
  
  #part 2, skipping borders
  for y in 1..<h-1:
    for x in 1..<w-1:
      result[1] += (int)grid.searchCrossMAS(x, y)

    Part 1 was done really quickly. Part 2 as well, but the result was not accepted…

    Turns out +MAS isn’t actually a thing :P

  • ystael@beehaw.org
    3·
    11 hours ago

    J

    Unsurprisingly this is the kind of problem that J is really good at. The dyadic case (table) of the adverb / is doing all the heavy lifting here: it makes a higher rank tensor by traversing items of the specified rank on each side and combining them according to the remaining frame of each side’s shape. The hard part is arranging the arguments so that your resulting matrix has its axes in the correct order.

    data_file_name =: '4.data'

NB. cutopen yields boxed lines, so unbox them and ravel items to make a letter matrix
grid =: ,. > cutopen fread data_file_name
NB. pad the grid on every side with #'XMAS' - 1 spaces
hpadded_grid =: (('   ' &amp; ,) @: (, &amp; '   '))"1 grid
padded_grid =: (3 1 $ ' ') , hpadded_grid , (3 1 $ ' ')
NB. traversal vectors
directions =: 8 2 $ 1 0 1 1 0 1 _1 1 _1 0 _1 _1 0 _1 1 _1
NB. rpos cpos matches rdir cdir if the string starting at rpos cpos in
NB. direction rdir cdir is the string we want
matches =: 4 : 0
*/ ,'XMAS' -: padded_grid {~ &lt;"1 x +"1 y *"1 0 i. 4
)"1
positions =: (3 + i. 0 { $ grid) ,"0/ (3 + i. 1 { $ grid)
result1 =: +/, positions matches/ directions

NB. pairs of traversal vectors
x_directions =: 4 2 2 $ 1 1 _1 1 1 1 1 _1 _1 _1 _1 1 _1 _1 1 _1
NB. rpos cpos x_matches 2 2 $ rdir1 cdir1 rdir2 cdir2 if there is an 'A' at
NB. rpos cpos and the string in each of dir1 and dir2 centered at rpos cpos
NB. is the string we want
x_matches =: 4 : 0
NB. (2 2 $ rdir1 cdir1 rdir2 cdir2) *"1 0/ (_1 + i.3) yields a matrix
NB. 2 3 $ (_1 * dir1) , (0 * dir1) , (1 * dir1) followed by the same for dir2
*/ ,'MAS' -:"1 padded_grid {~ &lt;"1 x +"1 y *"1 0/ _1 + i. 3
)"1 2
result2 =: +/, positions x_matches/ x_directions
  • Rin@lemm.ee
    1·
    10 hours ago

    This one was a little bit of a pain. I loved it.

    TypeScript

    Solution 
    import { AdventOfCodeSolutionFunction } from "./solutions";

enum Direction {
    UP,
    UP_RIGHT,
    RIGHT,
    BOTTOM_RIGHT,
    BOTTOM,
    BOTTOM_LEFT,
    LEFT,
    UP_LEFT,
};

const ALL_DIRECTIONS = [
    Direction.RIGHT,
    Direction.BOTTOM_RIGHT,
    Direction.BOTTOM,
    Direction.BOTTOM_LEFT,
    Direction.LEFT,
    Direction.UP_LEFT,
    Direction.UP,
    Direction.UP_RIGHT,
];

const check_coords = (grid: Array<Array<string>>, x: number, y: number) => {
    return y >= grid.length ||
        y < 0 ||
        x >= grid[y].length ||
        x < 0
}

const search_direction = (grid: Array<Array<string>>, x: number, y: number, direction: Direction, find: Array<string>) => {
    // exit conditions
    // no more to find
    if (find.length == 0)
        return 1; // found the end

    // invalid coords
    if (check_coords(grid, x, y))
        return 0;

    // make new mutable list
    const newFind = [...find];
    const searchChar = newFind.shift();

    // wrong character
    if (grid[y][x] !== searchChar)
        return 0;

    switch (direction) {
        case Direction.UP:
            return search_direction(grid, x, y + 1, direction, newFind);

        case Direction.UP_RIGHT:
            return search_direction(grid, x + 1, y + 1, direction, newFind);

        case Direction.RIGHT:
            return search_direction(grid, x + 1, y, direction, newFind);

        case Direction.BOTTOM_RIGHT:
            return search_direction(grid, x + 1, y - 1, direction, newFind);

        case Direction.BOTTOM:
            return search_direction(grid, x, y - 1, direction, newFind);

        case Direction.BOTTOM_LEFT:
            return search_direction(grid, x - 1, y - 1, direction, newFind);

        case Direction.LEFT:
            return search_direction(grid, x - 1, y, direction, newFind);

        case Direction.UP_LEFT:
            return search_direction(grid, x - 1, y + 1, direction, newFind);

        default:
            return 0;
    }
}

const part_1_search = (grid: Array<Array<string>>, x: number, y: number, find: Array<string>) => {
    return ALL_DIRECTIONS.reduce<number>(
        (instances, direction) =>
            instances + search_direction(grid, x, y, direction, find),
        0
    );
}

const part_2_search = (grid: Array<Array<string>>, x: number, y: number, find: Array<string>) => {
    return (
        search_direction(grid, x - 1, y + 1, Direction.BOTTOM_RIGHT, find) +
        search_direction(grid, x + 1, y + 1, Direction.BOTTOM_LEFT, find) +
        search_direction(grid, x - 1, y - 1, Direction.UP_RIGHT, find) +
        search_direction(grid, x + 1, y - 1, Direction.UP_LEFT, find)
    ) == 2 ? 1 : 0;
}

export const solution_4: AdventOfCodeSolutionFunction = (input) => {
    const grid = input.split("\n").map(st => st.trim()).map(v => v.split(""));

    let part_1 = 0;
    let part_2 = 0;

    const find_1 = "XMAS".split("");
    const find_2 = "MAS".split("");

    for (let y = 0; y < grid.length; y++) {
        for (let x = 0; x < grid[y].length; x++) {
            part_1 += part_1_search(grid, x, y, find_1);
            part_2 += part_2_search(grid, x, y, find_2);
        }
    }

    return {
        part_1,
        part_2,
    };
}

    Felt like this code quality is better than what I usually output :)

  • reboot6675@sopuli.xyz
    1·
    12 hours ago

    Go

    Just a bunch of ifs and bounds checking. Part 2 was actually simpler.

    Code 
    func part1(W [][]rune) {
	m := len(W)
	n := len(W[0])
	xmasCount := 0

	for i := 0; i < m; i++ {
		for j := 0; j < n; j++ {
			if W[i][j] != 'X' {
				continue
			}
			if j < n-3 && W[i][j+1] == 'M' && W[i][j+2] == 'A' && W[i][j+3] == 'S' {
				// Horizontal left to right
				xmasCount++
			}
			if j >= 3 && W[i][j-1] == 'M' && W[i][j-2] == 'A' && W[i][j-3] == 'S' {
				// Horizontal right to left
				xmasCount++
			}
			if i < m-3 && W[i+1][j] == 'M' && W[i+2][j] == 'A' && W[i+3][j] == 'S' {
				// Vertical up to down
				xmasCount++
			}
			if i >= 3 && W[i-1][j] == 'M' && W[i-2][j] == 'A' && W[i-3][j] == 'S' {
				// Vertical down to up
				xmasCount++
			}
			if j < n-3 && i < m-3 && W[i+1][j+1] == 'M' && W[i+2][j+2] == 'A' && W[i+3][j+3] == 'S' {
				// Diagonal left to right and up to down
				xmasCount++
			}
			if j >= 3 && i < m-3 && W[i+1][j-1] == 'M' && W[i+2][j-2] == 'A' && W[i+3][j-3] == 'S' {
				// Diagonal right to left and up to down
				xmasCount++
			}
			if j < n-3 && i >= 3 && W[i-1][j+1] == 'M' && W[i-2][j+2] == 'A' && W[i-3][j+3] == 'S' {
				// Diagonal left to right and down to up
				xmasCount++
			}
			if j >= 3 && i >= 3 && W[i-1][j-1] == 'M' && W[i-2][j-2] == 'A' && W[i-3][j-3] == 'S' {
				// Diagonal right to left and down to up
				xmasCount++
			}
		}
	}

	fmt.Println(xmasCount)
}

func part2(W [][]rune) {
	m := len(W)
	n := len(W[0])
	xmasCount := 0

	for i := 0; i <= m-3; i++ {
		for j := 0; j <= n-3; j++ {
			if W[i+1][j+1] != 'A' {
				continue
			}
			if W[i][j] == 'M' && W[i][j+2] == 'M' && W[i+2][j] == 'S' && W[i+2][j+2] == 'S' {
				xmasCount++
			} else if W[i][j] == 'M' && W[i][j+2] == 'S' && W[i+2][j] == 'M' && W[i+2][j+2] == 'S' {
				xmasCount++
			} else if W[i][j] == 'S' && W[i][j+2] == 'S' && W[i+2][j] == 'M' && W[i+2][j+2] == 'M' {
				xmasCount++
			} else if W[i][j] == 'S' && W[i][j+2] == 'M' && W[i+2][j] == 'S' && W[i+2][j+2] == 'M' {
				xmasCount++
			}
		}
	}

	fmt.Println(xmasCount)
}

func main() {
	file, _ := os.Open("input.txt")
	defer file.Close()
	scanner := bufio.NewScanner(file)

	var W [][]rune
	for scanner.Scan() {
		line := scanner.Text()
		W = append(W, []rune(line))
	}

	part1(W)
	part2(W)
}
  • vole@lemmy.worldEnglish
    1·
    12 hours ago

    Raku

    Oof, my struggle to make custom index walking paths for part 1 did not pay off for part 2.

    Solution 
    sub MAIN($input) {
    my $file = (open $input).slurp;
    my @grid is List = $file.lines».comb».list;
    my @transposedGrid is List = [Z] @grid;
    my @reversedGrid is List = @grid».reverse;
    my @transposedReversedGrid is List = @transposedGrid».reverse;

    my @horizontalScanRows is List = generateScanHorizontal(@grid);
    my @transposedHorizontalScanRows is List = generateScanHorizontal(@transposedGrid);

    my @part-one-counts = [];
    @part-one-counts.push(count-xmas(@grid, @horizontalScanRows)); # Right
    @part-one-counts.push(count-xmas(@transposedGrid, @transposedHorizontalScanRows)); # Down
    @part-one-counts.push(count-xmas(@reversedGrid, @horizontalScanRows)); # Left
    @part-one-counts.push(count-xmas(@transposedReversedGrid, @transposedHorizontalScanRows)); # Up

    my @diagonalScanRows is List = generateScanDiagonal(@grid);
    my @transposedDiagonalScanRows is List = generateScanDiagonal(@transposedGrid);
    @part-one-counts.push(count-xmas(@grid, @diagonalScanRows)); # Down Right
    @part-one-counts.push(count-xmas(@grid, @diagonalScanRows».reverse)); # Up Left
    @part-one-counts.push(count-xmas(@reversedGrid, @diagonalScanRows)); # Down Left
    @part-one-counts.push(count-xmas(@reversedGrid, @diagonalScanRows».reverse)); # Up Right

    my $part-one-solution = @part-one-counts.sum;
    say "part 1: $part-one-solution";


    my @part-two-counts = [];
    @part-two-counts.push(countGridMatches(@grid, (<M . S>,<. A .>,<M . S>)));
    @part-two-counts.push(countGridMatches(@grid, (<S . S>,<. A .>,<M . M>)));
    @part-two-counts.push(countGridMatches(@grid, (<S . M>,<. A .>,<S . M>)));
    @part-two-counts.push(countGridMatches(@grid, (<M . M>,<. A .>,<S . S>)));

    my $part-two-solution = @part-two-counts.sum;
    say "part 2: $part-two-solution";

}

sub count-xmas(@grid, @scanRows) {
    my $xmas-count = 0;
    for @scanRows -> @scanRow {
        my $xmas-pos = 0;
        for @scanRow -> @pos {
            my $char = @grid[@pos[0]][@pos[1]];
            if "X" eq $char {
                $xmas-pos = 1;
            }elsif <X M A S>[$xmas-pos] eq $char {
                if $xmas-pos == 3 {
                    $xmas-pos = 0;
                    $xmas-count += 1;
                } else {
                    $xmas-pos += 1;
                }
            } else {
                $xmas-pos = 0;
            }
        }
    }
    return $xmas-count;
}

sub generateScanHorizontal(@grid) {
    # Horizontal
    my $rows = @grid.elems;
    my $cols = @grid[0].elems;
    my @scanRows = ();
    for 0..^$rows -> $row {
        my @scanRow = ();
        for 0..^$cols -> $col {
            @scanRow.push(($row, $col));
        }
        @scanRows.push(@scanRow);
    }
    return @scanRows.List».List;
}

sub generateScanDiagonal(@grid) {
    # Down-right diagonal
    my $rows = @grid.elems;
    my $cols = @grid[0].elems;
    my @scanRows = ();
    for 0..^($rows + $cols - 1) -> $diag {
        my @scanRow = ();
        my $starting-row = max(-$cols + $diag + 1, 0);
        my $starting-col = max($rows - $diag - 1, 0);
        my $diag-len = min($rows - $starting-row, $cols - $starting-col);
        for 0..^$diag-len -> $diag-pos {
            @scanRow.push(($starting-row + $diag-pos, $starting-col + $diag-pos));
        }
        @scanRows.push(@scanRow);
    }
    return @scanRows.List».List;
}

sub countGridMatches(@grid, @needle) {
    my $count = 0;
    for 0..(@grid.elems - @needle.elems) -> $top {
        TOP-LEFT:
        for 0..(@grid[$top].elems - @needle[0].elems) -> $left {
            for 0..^@needle.elems -> $row-offset {
                for 0..^@needle[$row-offset].elems -> $col-offset {
                    my $needle-char = @needle[$row-offset][$col-offset];
                    next if $needle-char eq ".";
                    next TOP-LEFT if $needle-char ne @grid[$top+$row-offset][$left+$col-offset];
                }
            }
            $count += 1;
        }
    }
    return $count;
}

    github

  • SteveDinn@lemmy.caEnglish
    1·
    12 hours ago

    C#

    namespace Day04;

static class Program
{
    public record struct Point(int Row, int Col);

    static void Main(string[] args)
    {
        var sample = File.ReadAllLines("sample.txt");
        var data = File.ReadAllLines("data.txt");

        Console.WriteLine($"Part 1 (sample): {SolvePart1(sample)}");
        Console.WriteLine($"Part 1 (data): {SolvePart1(data)}");

        Console.WriteLine($"Part 2 (sample): {SolvePart2(sample)}");
        Console.WriteLine($"Part 2 (data): {SolvePart2(data)}");
    }

    private static readonly string Search = "XMAS";

    private static readonly Func<Point, Point>[] DirectionalMoves =
    {
        p => new Point(p.Row + 1, p.Col),
        p => new Point(p.Row + 1, p.Col + 1),
        p => new Point(p.Row, p.Col + 1),
        p => new Point(p.Row - 1, p.Col + 1),
        p => new Point(p.Row - 1, p.Col),
        p => new Point(p.Row - 1, p.Col - 1),
        p => new Point(p.Row, p.Col - 1),
        p => new Point(p.Row + 1, p.Col - 1),
    };

    private static readonly Func<Point, Point>[] ForwardSlashMoves =
    {
        p => new Point(p.Row - 1, p.Col - 1),
        p => new Point(p.Row + 1, p.Col + 1),
    };
    
    private static readonly Func<Point, Point>[] BackSlashMoves =
    {
        p => new Point(p.Row + 1, p.Col - 1),
        p => new Point(p.Row - 1, p.Col + 1),
    };

    static long SolvePart1(string[] data)
    {
        return Enumerable
            .Range(0, data.Length)
            .SelectMany(row => Enumerable.Range(0, data[row].Length)
                .Select(col => new Point(row, col)))
            .Where(p => IsMatch(data, p, Search[0]))
            .Sum(p => DirectionalMoves
                .Count(move => DeepMatch(data, move(p), move, Search, 1)));
    }

    static long SolvePart2(string[] data)
    {
        return Enumerable
            .Range(0, data.Length)
            .SelectMany(row => Enumerable.Range(0, data[row].Length)
                .Select(col => new Point(row, col)))
            .Where(p => IsMatch(data, p, 'A'))
            .Count(p => CheckDiagonalMoves(data, p, ForwardSlashMoves)
                        && CheckDiagonalMoves(data, p, BackSlashMoves));
    }

    static bool CheckDiagonalMoves(string[] data, Point p, Func<Point, Point>[] moves)
        => (IsMatch(data, moves[0](p), 'S') && IsMatch(data, moves[1](p), 'M'))
           || (IsMatch(data, moves[0](p), 'M') && IsMatch(data, moves[1](p), 'S'));

    static bool DeepMatch(string[] data, Point p, Func<Point, Point> move, string search, int searchIndex) =>
        (searchIndex >= search.Length) ? true :
        (!IsMatch(data, p, search[searchIndex])) ? false :
        DeepMatch(data, move(p), move, search, searchIndex + 1);

    static bool IsMatch(string[] data, Point p, char searchChar)
        => IsInBounds(data, p) && (data[p.Row][p.Col] == searchChar);

    static bool IsInBounds(string[] data, Point p) =>
        (p.Row >= 0) && (p.Col >= 0) && (p.Row < data.Length) && (p.Col < data[0].Length);
}
  • proved_unglue
    1·
    12 hours ago

    Kotlin

    fun part1(input: String): Int {
    return countWordOccurrences(input.lines())
}

fun part2(input: String): Int {
    val grid = input.lines().map(String::toList)
    var count = 0
    for (row in 1..grid.size - 2) {
        for (col in 1..grid[row].size - 2) {
            if (grid[row][col] == 'A') {
                count += countCrossMatch(grid, row, col)
            }
        }
    }
    return count
}

private fun countCrossMatch(grid: List<List<Char>>, row: Int, col: Int): Int {
    val surroundingCorners = listOf(
        grid[row - 1][col - 1], // upper left
        grid[row - 1][col + 1], // upper right
        grid[row + 1][col - 1], // lower left
        grid[row + 1][col + 1], // lower right
    )
    // no matches:
    //   M S   S M
    //    A     A
    //   S M   M S
    return if (surroundingCorners.count { it == 'M' } == 2
        && surroundingCorners.count { it == 'S' } == 2
        && surroundingCorners[0] != surroundingCorners[3]
    ) 1 else 0
}

private fun countWordOccurrences(matrix: List<String>): Int {
    val rows = matrix.size
    val cols = if (rows > 0) matrix[0].length else 0
    val directions = listOf(
        Pair(0, 1),   // Horizontal right
        Pair(1, 0),   // Vertical down
        Pair(1, 1),   // Diagonal down-right
        Pair(1, -1),  // Diagonal down-left
        Pair(0, -1),  // Horizontal left
        Pair(-1, 0),  // Vertical up
        Pair(-1, -1), // Diagonal up-left
        Pair(-1, 1)   // Diagonal up-right
    )

    fun isWordAt(row: Int, col: Int, word: String, direction: Pair<Int, Int>): Boolean {
        val (dx, dy) = direction
        for (i in word.indices) {
            val x = row + i * dx
            val y = col + i * dy
            if (x !in 0 until rows || y !in 0 until cols || matrix[x][y] != word[i]) {
                return false
            }
        }
        return true
    }

    var count = 0

    for (row in 0 until rows) {
        for (col in 0 until cols) {
            for (direction in directions) {
                if (isWordAt(row, col, "XMAS", direction)) {
                    count++
                }
            }
        }
    }

    return count
}
  • mykl@lemmy.world
    2·
    10 hours ago

    Uiua

    Just part1 for now as I need to walk the dog :-)

    [edit] Part 2 now added, and a nicer approach than Part 1 in my opinion, if you’re able to keep that many dimensions straight in your head :-)

    [edit 2] Tightened it up a bit more.

    Grid ← ⊜∘⊸≠@\n "MMMSXXMASM\nMSAMXMSMSA\nAMXSXMAAMM\nMSAMASMSMX\nXMASAMXAMM\nXXAMMXXAMA\nSMSMSASXSS\nSAXAMASAAA\nMAMMMXMMMM\nMXMXAXMASX"

≡⍉⍉×⇡4¤[1_0 0_1 1_1 1_¯1]         # Use core dirs to build sets of 4-offsets.
↯∞_2⇡△ Grid                       # Get all possible starting points.
&p/+♭⊞(+∩(≍"XMAS")⇌.⬚@.⊡:Grid≡+¤) # Part 1. Join the two into a table, use to pick 4-elements, check, count.

Diags   ← [[¯. 1_1] [¯. 1_¯1]]
BothMas ← /×≡(+∩(≍"MS")⇌.)⬚@.⊡≡+Diags¤¤ # True if both diags here are MAS.
&p/+≡BothMas⊚="A"⟜¤Grid                 # Part 2. For all "A"s in grid, check diags, count where good.
      • mykl@lemmy.world
        2·
        11 hours ago

        The operators have all got ascii names you can type, and the formatter converts them to the symbols. It’s a bit odd but really worthwhile, as you get access to the powerful array handling functionality that made solving today’s challenges so much more straightforward than in other languages.

  • sjmulder@lemmy.sdf.org
    2·
    16 hours ago

    C

    What can I say, bunch of for loops! I add a 3 cell border to avoid having to do bounds checking in the inner loops.

    Code 
    #include "common.h"
#define GZ 146

int main(int argc, char **argv) {
	static char g[GZ][GZ];
	static const char w[] = "XMAS";
	int p1=0,p2=0, x,y, m,i;

	if (argc > 1) DISCARD(freopen(argv[1], "r", stdin));
	for (y=3; y<GZ && fgets(g[y]+3, GZ-3, stdin); y++) ;

	for (y=3; y<GZ-3; y++)
	for (x=3; x<GZ-3; x++) {
		for (m=1,i=0; i<4; i++) {m &= g[y+i][x]==w[i];} p1+=m;
		for (m=1,i=0; i<4; i++) {m &= g[y-i][x]==w[i];} p1+=m;
		for (m=1,i=0; i<4; i++) {m &= g[y][x+i]==w[i];} p1+=m;
		for (m=1,i=0; i<4; i++) {m &= g[y][x-i]==w[i];} p1+=m;
		for (m=1,i=0; i<4; i++) {m &= g[y+i][x+i]==w[i];} p1+=m;
		for (m=1,i=0; i<4; i++) {m &= g[y-i][x-i]==w[i];} p1+=m;
		for (m=1,i=0; i<4; i++) {m &= g[y+i][x-i]==w[i];} p1+=m;
		for (m=1,i=0; i<4; i++) {m &= g[y-i][x+i]==w[i];} p1+=m;

		p2 += g[y+1][x+1]=='A' &&
		      ((g[y][x]  =='M' && g[y+2][x+2]=='S')  ||
		       (g[y][x]  =='S' && g[y+2][x+2]=='M')) &&
		      ((g[y+2][x]=='M' && g[y][x+2]  =='S')  ||
		       (g[y+2][x]=='S' && g[y][x+2]  =='M'));
	}

	printf("04: %d %d\n", p1, p2);
}

    https://github.com/sjmulder/aoc/blob/master/2024/c/day04.c

  • Leo Uino@lemmy.sdf.org
    4·
    19 hours ago

    Haskell

    Popular language this year :)

    I got embarrassingly stuck on this one trying to be clever with list operations. Then I realized I should just use an array…

    import Data.Array.Unboxed (UArray)
import Data.Array.Unboxed qualified as A
import Data.Bifunctor

readInput :: String -> UArray (Int, Int) Char
readInput s =
  let rows = lines s
      n = length rows
   in A.listArray ((1, 1), (n, n)) $ concat rows

s1 `eq` s2 = s1 == s2 || s1 == reverse s2

part1 arr = length $ filter isXmas $ concatMap lines $ A.indices arr
  where
    isXmas ps = all (A.inRange $ A.bounds arr) ps && map (arr A.!) ps `eq` "XMAS"
    lines p = [take 4 $ iterate (bimap (+ di) (+ dj)) p | (di, dj) <- [(1, 0), (0, 1), (1, 1), (1, -1)]]

part2 arr = length $ filter isXmas innerPoints
  where
    innerPoints =
      let ((i1, j1), (i2, j2)) = A.bounds arr
       in [(i, j) | i <- [i1 + 1 .. i2 - 1], j <- [j1 + 1 .. j2 - 1]]
    isXmas p = up p `eq` "MAS" && down p `eq` "MAS"
    up (i, j) = map (arr A.!) [(i + 1, j - 1), (i, j), (i - 1, j + 1)]
    down (i, j) = map (arr A.!) [(i - 1, j - 1), (i, j), (i + 1, j + 1)]

main = do
  input <- readInput <$> readFile "input04"
  print $ part1 input
  print $ part2 input
  • janAkali@lemmy.oneEnglish
    4·
    19 hours ago

    Nim

    Could be done more elegantly, but I haven’t bothered yet.

    proc solve(input: string): AOCSolution[int, int] =
  var lines = input.splitLines()

  block p1:
    # horiz
    for line in lines:
      for i in 0..line.high-3:
        if line[i..i+3] in ["XMAS", "SAMX"]:
          inc result.part1

    for y in 0..lines.high-3:
      #vert
      for x in 0..lines[0].high:
        let word = collect(for y in y..y+3: lines[y][x])
        if word in [@"XMAS", @"SAMX"]:
          inc result.part1

      #diag \
      for x in 0..lines[0].high-3:
        let word = collect(for d in 0..3: lines[y+d][x+d])
        if word in [@"XMAS", @"SAMX"]:
          inc result.part1

      #diag /
      for x in 3..lines[0].high:
        let word = collect(for d in 0..3: lines[y+d][x-d])
        if word in [@"XMAS", @"SAMX"]:
          inc result.part1

  block p2:
    for y in 0..lines.high-2:
      for x in 0..lines[0].high-2:
        let diagNW = collect(for d in 0..2: lines[y+d][x+d])
        let diagNE = collect(for d in 0..2: lines[y+d][x+2-d])
        if diagNW in [@"MAS", @"SAM"] and diagNE in [@"MAS", @"SAM"]:
          inc result.part2

    Codeberg repo