diff --git a/day10/sol.py b/day10/sol.py
index 0f1863c..137f617 100644
--- a/day10/sol.py
+++ b/day10/sol.py
@@ -31,13 +31,6 @@ for i, row in enumerate(map):
 
 #print(grid)
 
-def draw(grid):
-    y = max([i for i,j in grid.keys()])
-    x = max([j for i,j in grid.keys()])
-    for i in range(y+1):
-        print("".join(".+O"[grid[i,j]] if (i,j) in grid else "x" for j in range(x+1)))
-    print()
-
 def find_loop(grid, start):
     front = [(0,start)]
     dist = {}
@@ -71,57 +64,61 @@ def find_loop(grid, start):
 
 def enclosedby(grid, points):
     # upsample by 3x3
-    fill = {}
-    for i,j in grid:
-        for k in range(3):
-            for l in range(3):
-                fill[i*3+k,j*3+l] = 0
-    #print(*sorted(fill.keys()), sep="\n")
+    fill = [[0]*(X*3) for _ in range(Y*3)]
     for i,j in points:
         d = grid[i,j]
         if   d == N|S: t=[[0,1,0],[0,1,0],[0,1,0]]
         elif d == N|W: t=[[0,1,0],[1,1,0],[0,0,0]]
         elif d == N|E: t=[[0,1,0],[0,1,1],[0,0,0]]
         elif d == S|W: t=[[0,0,0],[1,1,0],[0,1,0]]
-        elif d == S|E:t=[[0,0,0],[0,1,1],[0,1,0]]
-        elif d == E|W:t=[[0,0,0],[1,1,1],[0,0,0]]
+        elif d == S|E: t=[[0,0,0],[0,1,1],[0,1,0]]
+        elif d == E|W: t=[[0,0,0],[1,1,1],[0,0,0]]
         else: raise Exception("invalid d=%d at (%s,%s)" % (d, i, j))
         for k in range(3):
             for l in range(3):
-                fill[i*3+k,j*3+l] = t[k][l]
-    #print(fill)
+                fill[i*3+k][j*3+l] = t[k][l]
+
+    def draw(fill):
+        for row in fill:
+            print("".join(".+O"[f] for f in row))
+
+    draw(fill)
 
     # fill edges
     for i in range(Y*3):
-        if fill[i,0] == 0: fill[i,0] = 2
-        if fill[i,X*3-1] == 0: fill[i,X*3-1] = 2
+        if fill[i][  0  ] == 0: fill[i][  0  ] = 2
+        if fill[i][X*3-1] == 0: fill[i][X*3-1] = 2
     for j in range(X*3):
-        if fill[0,j] == 0: fill[0,j] = 2
-        if fill[Y*3-1,j] == 0: fill[Y*3-1,j] = 2
+        if fill[  0  ][j] == 0: fill[  0  ][j] = 2
+        if fill[Y*3-1][j] == 0: fill[Y*3-1][j] = 2
 
     # flood fill
+    next = {}
     def set(i,j):
-        if (i,j) in fill:
-            if fill[i,j] == 0:
+        if 0 <= i < Y*3 and 0 <= j < X*3:
+            if fill[i][j] == 0:
                 next[i,j] = 2
     while True:
         #draw(fill)
-        next = {}
-        for i,j in fill:
-            if fill[i,j] == 2:
-                set(i-1,j)
-                set(i+1,j)
-                set(i,j-1)
-                set(i,j+1)
-        if not next:
-            break
-        fill.update(next)
+        next.clear()
+        for i in range(Y*3):
+            for j in range(X*3):
+                if fill[i][j] == 2:
+                    set(i-1,j)
+                    set(i+1,j)
+                    set(i,j-1)
+                    set(i,j+1)
+        if next:
+            for (i,j),c in next.items():
+                fill[i][j] = c
+            continue
+        break
     draw(fill)
 
     # downsample
     inside = []
     for i,j in grid:
-        f = [fill[i*3+k,j*3+l]==0 for k in range(3) for l in range(3)]
+        f = [fill[i*3+k][j*3+l]==0 for k in range(3) for l in range(3)]
         if all(f):
             inside.append((i,j))