disallow wires with only one edge and discourage empty tiles

gen.py

@@ -37,7 +37,17 @@ def isWireConnected(puzzle,x,y):
     return True
 
 def gettile():
-    return (WIRE, [i for i in range(4) if random.random() < 0.4])
+    while True:
+        tile = (WIRE, [i for i in range(4) if random.random() < 0.4])
+        if len(tile[1]) == 1:
+            if random.random() < 0.2:
+                return (SOURCE, tile[1])
+        elif len(tile[1]) == 0:
+            if random.random() < 0.2:
+                return tile
+        else:
+            return tile
+    
 
 def consistent(puzzle,x,y):
     if not isWireConnected(puzzle,x,y):
@@ -102,6 +112,13 @@ def genpuzzle(w,h=None,seed=0):
                 puzzle[y][x] = gettile()
     
     numsinks = (w*h//10) + 1
+    # add linked sink to each source
+    for y in range(h):
+        for x in range(w):
+            if puzzle[y][x][0] == SOURCE:
+                x2,y2 = reachable(puzzle,x,y)
+                puzzle[y2][x2] = (SINK,puzzle[y2][x2][1])
+    
     for _ in range(numsinks):
         x = random.randint(0,w-1)
         y = random.randint(0,h-1)