day3.mar

import ../stdlib.mar

fun is_digit(char: Char): Bool { {#0..=#9}.contains(char) }
fun is_symbol(char: Char): Bool { not(char.is_digit()) and char != #. }

fun main(): Never {
  var grid = read_file("advent/day3.big").unwrap().to_string().into_grid()
  var grid = uninitialized_slice[Slice[Char]](lines.len)
  for it in lines.iter().enumerate() do grid.get_ref(it.index).* = it.item.chars()
  println(grid.width())
  println(grid.height())

  var sum = 0
  for y in 0..grid.height() do
    for x in 0..grid.width() do {
      var char = grid.get(x, y)
      if char.is_digit() and not(grid.get(x - 1, y).is_digit())
      then {
        var end = x
        loop if grid.get(end, y).is_digit() then end = end + 1 else break
        var num = grid.get(y).subslice(x..end).parse_int()

        var adjacent = list[Point[Int]]()
        for xx in {x - 1}..=end do {
          adjacent.&.push(Point { x = xx, y = y - 1 })
          adjacent.&.push(Point { x = xx, y = y + 1 })
        }
        adjacent.&.push(Point { x = x - 1, y })
        adjacent.&.push(Point { x = end, y })

        var next_to_symbol = false
        for pos in adjacent do
          if grid.get(pos.x, pos.y).is_symbol() then next_to_symbol = true()

        if next_to_symbol then {
          print(num)
          println(" is a part")
          sum = sum.add(num)
        } else {
          print(num)
          println(" is NOT a part")
        }
      }
    }

  println(sum)

  exit(0)
}

fun into_grid(input: String): Grid {
  var lines = input.lines()
  var width = lines.get(0).len
  var height = lines.len
  var cells = uninitialized_matrix[Char](width @ lines.len)

  for it in lines.iter().enumerate() do
    cells.get_ref(it.index).* = it.item.chars()
  Grid { cells }
}

struct Grid { cells: Matrix[Char] }

fun width(grid: Slice[Slice[Char]]): Int { grid.get(0).len }
fun height(grid: Slice[Slice[Char]]): Int { grid.len }
fun get(grid: Slice[Slice[Char]], x: Int, y: Int): Char {
  if x < 0 or x >= grid.width() or y < 0 or y >= grid.height()
  then return #.
  grid.get(y).get(x)
}