a simple shortest-path solver

I'm trying to remove some drudgery:
  https://merveilles.town/@akkartik/112086504775924524

screens/main

@@ -15,6 +15,7 @@ function car.load()
   car.resize()
   level_state = load_level(levels[curr_level])
   player = player_state(level_state)
+  path = unwind_path(find_path(level_state, {x=15,y=12}, {x=12, y=9}))
 end
 
 function car.draw()
@@ -25,6 +26,7 @@ function car.draw()
   draw_buttons()
   draw_level_number()
   draw_win_state()
+  draw_path(path)
   draw_hud()
 end
 

screens/solve

@@ -0,0 +1,47 @@
+function find_path(level, src, dst)
+  local done = initialize_array(false, lh, lw)
+  local cands = {}
+  table.insert(cands, {x=src.x, y=src.y})
+  while #cands > 0 do
+    local cand = table.remove(cands, 1)
+    local x,y = cand.x, cand.y
+    if x == dst.x and y == dst.y then return cand end
+    if y >= 1 and y <= lh and x >= 1 and x <= lw and not done[y][x] then
+      done[y][x] = true
+      local curr = level[y][x]
+      if curr ~= CELL_WALL and curr ~= CELL_CRATE and curr ~= CELL_CRATE_ON_TARGET then
+        table.insert(cands, {x=x-1, y=y, prev=cand})
+        table.insert(cands, {x=x+1, y=y, prev=cand})
+        table.insert(cands, {x=x, y=y-1, prev=cand})
+        table.insert(cands, {x=x, y=y+1, prev=cand})
+      end end end end
+
+function unwind_path(c)
+  local result = {}
+  while c do
+    table.insert(result, {x=c.x, y=c.y})
+    c = c.prev
+  end
+  return result
+end
+
+function draw_path(path)
+  color(1,0,0)
+  for _,cell in ipairs(path) do
+    rect('line', left+(cell.x-1)*side, top+(cell.y-1)*side, side, side)
+  end end
+
+function initialize_array(val, dim, ...)
+  local result = {}
+  local other_dims = {...}
+  if #other_dims == 0 then
+    for i=1,dim do
+      table.insert(result, val)
+    end
+  else
+    for i=1,dim do
+      table.insert(result, initialize_array(val, ...))
+    end
+  end
+  return result
+end