fix solve() logic error

Sketch.py

@@ -41,4 +41,5 @@ class Sketch(object):
         r = s.solve()
         solved_vars = r.xf
         for i in range(len(solved_vars)):
-            varid_to_shape_var[i].setVar(solved_vars[i])
+            varid_to_shape_var[i][0].setVar(varid_to_shape_var[i][1],
+                    solved_vars[i])