[Day 15] Work on problem

Author: goggle

src/day15.jl

@@ -5,24 +5,49 @@ using AdventOfCode2024
 
 function day15(input::String = readInput(joinpath(@__DIR__, "..", "data", "day15.txt")))
     world, instructions = parse_input(input)
-    part1(world, instructions)
+    world_p1 = copy(world)
+    execute_instructions_p1!(world_p1, instructions)
+    p1 = total_gps(world_p1)
+    world_p2 = fill('.', (size(world) .* (1, 2))...)
+    for ind ∈ eachindex(IndexCartesian(), world)
+        if world[ind] == '#'
+            world_p2[ind[1],2*ind[2]-1] = '#'
+            world_p2[ind[1],2*ind[2]] = '#'
+        elseif world[ind] == 'O'
+            world_p2[ind[1],2*ind[2]-1] = '['
+            world_p2[ind[1],2*ind[2]] = ']'
+        elseif world[ind] == '@'
+            world_p2[ind[1],2*ind[2]-1] = '@'
+        end
+    end
+    execute_instructions_p2!(world_p2, instructions)
+    return world_p2
 end
 
 function parse_input(input)
     wo, ins = split(input, "\n\n")
-    return map(x -> x[1], reduce(vcat, permutedims.(map(x -> split(x, ""), split(wo))))), rstrip(ins)
+    return map(x -> x[1], reduce(vcat, permutedims.(map(x -> split(x, ""), split(wo))))), replace(ins, '\n' => "")
 end
 
-function part1(world, instructions)
+function execute_instructions_p1!(world, instructions)
     current = findall(x -> x == '@', world)[1]
-    world[start] = '.'
+    world[current] = '.'
     for instruction ∈ instructions
         next = current + _to_dir(instruction)
         if world[next] == '.'
             current = next
         elseif world[next] == 'O'
+            while world[next] ∉ ('.', '#')
+                next += _to_dir(instruction)
+            end
+            world[next] == '#' && continue
+            while next != current
+                pnext = next - _to_dir(instruction)
+                world[next], world[pnext] = world[pnext], world[next]
+                next = pnext
+            end
+            current = current + _to_dir(instruction)
         end
-
     end
 end
 
@@ -33,4 +58,80 @@ function _to_dir(c::Char)
     c == '<' && return CartesianIndex(0, -1)
 end
 
+function total_gps(world::Matrix{Char})
+    total = 0
+    for index ∈ findall(x -> x == 'O', world)
+        total += 100 * (index[1] - 1) + index[2] - 1
+    end
+    return total
+end
+
+function locate_box_complex!(tipping_positions::Set{CartesianIndex{2}}, move_positions::Set{CartesianIndex{2}}, world::Matrix{Char}, dir::CartesianIndex{2})
+    new_tipping_positions = Set{CartesianIndex{2}}()
+    for pos ∈ tipping_positions
+        push!(move_positions, pos)
+        if world[pos] == '['
+            lockpos = CartesianIndex(pos[1], pos[2] + 1)
+        elseif world[pos] == ']'
+            lockpos = CartesianIndex(pos[1], pos[2] - 1)
+        end
+        push!(move_positions, lockpos)
+        if world[pos + dir] == '#' || world[lockpos + dir] == '#'
+            return false
+        else
+            if world[pos + dir] ∈ ('[', ']')
+                push!(new_tipping_positions, pos + dir)
+            end
+            if world[lockpos + dir] ∈ ('[', ']')
+                push!(new_tipping_positions, lockpos + dir)
+            end
+        end
+    end
+    if !isempty(new_tipping_positions)
+        return locate_box_complex!(new_tipping_positions, move_positions, world, dir)
+    end
+    return true
+end
+
+function move!(move_positions::Set{CartesianIndex{2}}, world::Matrix{Char}, dir::CartesianIndex{2})
+    if dir[1] == -1
+        mpsorted = sort(collect(move_positions), by=x->x[1])
+    else
+        mpsorted = sort(collect(move_positions), by=x->x[1], rev=true)
+    end
+    for pos ∈ mpsorted
+        world[pos + dir], world[pos] = world[pos], world[pos + dir]
+    end
+end
+
+function execute_instructions_p2!(world, instructions)
+    current = findall(x -> x == '@', world)[1]
+    world[current] = '.'
+    for instruction ∈ instructions
+        dir = _to_dir(instruction)
+        next = current + dir
+        if world[next] == '.'
+            current = next
+        elseif world[next] ∈ ('[',']')
+            if instruction ∈ ('>', '<')
+                while world[next] ∉ ('.', '#')
+                    next += dir
+                end
+                world[next] == '#' && continue
+                while next != current
+                    pnext = next - dir
+                    world[next], world[pnext] = world[pnext], world[next]
+                    next = pnext
+                end
+                current = current + dir
+            else
+                move_positions = Set{CartesianIndex{2}}()
+                if locate_box_complex!(Set([next]), move_positions, world, dir)
+                    move!(move_positions, world, dir)
+                end
+            end
+        end
+    end
+end
+
 end # module