ignore swp

.gitignore

@@ -1 +1,2 @@
 */*/input
+.*.swp

12023/10/10.lua

@@ -0,0 +1,102 @@
+io.input("input")
+
+
+function coord(j,i) return {["j"]=j, ["i"]=i} end
+function same(c1, c2) 
+    if c1 and c2 then return c1.j==c2.j and c1.i==c2.i end
+    return false
+end
+
+function visited(c) return map[c.j][c.i].steps>=0 end
+
+function two_connections(j, i) -- returns two coordinates of connected tiles
+    if j<1 or j>nrows or i<1 or i>ncols then
+        return nil,nil
+    end
+    local co = coord(j,i)
+    local tile = map[j][i]
+    local c = tile.char
+    if c=="S" then --find
+        local matches = {}
+        local x, y = two_connections(j-1, i) -- north
+        if same(co,x) or same(co,y) then
+            print("N!")
+            table.insert(matches, coord(j-1, i))
+        end
+        x, y = two_connections(j+1, i) -- south
+        if same(co,x) or same(co,y) then
+            print("S!")
+            table.insert(matches, coord(j+1, i))
+        end
+        x, y = two_connections(j, i-1) -- west
+        if same(co,x) or same(co,y) then
+            print("W!")
+            table.insert(matches, coord(j, i-1))
+        end
+        x, y = two_connections(j, i+1) -- east
+        if same(co,x) or same(co,y) then
+            print("E!")
+            table.insert(matches, coord(j, i+1))
+        end
+        return table.unpack(matches)
+    elseif c=="|" then -- north and south 
+        return coord(j-1,i), coord(j+1,i)
+    elseif c=="-" then -- west and east
+        return coord(j,i-1), coord(j,i+1)
+    elseif c=="L" then --  north and east
+        return coord(j-1,i), coord(j,i+1)
+    elseif c=="J" then --  north and west
+        return coord(j-1,i), coord(j,i-1)
+    elseif c=="7" then --  south and west
+        return coord(j+1,i), coord(j,i-1)
+    elseif c=="F" then --  south and east 
+        return coord(j+1,i), coord(j,i+1)
+    end
+    return nil, nil
+end
+
+map = {}
+
+start = {}
+j = 1
+for line in io.lines() do
+    row = {}
+    i = 1
+    for c in line:gmatch("[%|%-LJ7F%.S]") do
+        tile = { char = c, steps = -1 }
+        if c=="S" then
+            start = coord(j, i)
+            tile.steps = 0
+        end
+
+        table.insert(row, tile)
+        i = i + 1
+    end
+    ncols = i-1
+
+    table.insert(map, row)
+    j = j + 1
+end
+nrows = j-1
+print(map[start.j][start.i].char, start.j, start.i)
+
+checking = {start}
+maxsteps = 0
+repeat
+    check = table.remove(checking,1)
+    steps = map[check.j][check.i].steps 
+    if steps>maxsteps then maxsteps=steps end
+--    print(steps, "checking", check.j, check.i, map[check.j][check.i].char)
+    x, y = two_connections(check.j,check.i)
+    if not visited(x) then
+        map[x.j][x.i].steps = steps+1
+        table.insert(checking,x)
+    end
+    if not visited(y) then
+        map[y.j][y.i].steps = steps+1
+        table.insert(checking,y)
+    end
+--    print(map[x.j][x.i].char, map[y.j][y.i].char)
+until #checking==0
+
+print("part 1", maxsteps, steps)

12023/10/test

@@ -0,0 +1,5 @@
+-L|F7
+7S-7|
+L|7||
+-L-J|
+L|-JF

12023/10/test2

@@ -0,0 +1,5 @@
+7-F7-
+.FJ|7
+SJLL7
+|F--J
+LJ.LJ