diff --git a/cyaron/graph.py b/cyaron/graph.py
index 8e54211..820e47e 100644
--- a/cyaron/graph.py
+++ b/cyaron/graph.py
@@ -67,6 +67,7 @@ def tree(point_count, chain=0, flower=0, **kwargs):
         weight_limit = kwargs.get("weight_limit", (1, 1))
         if not isinstance(weight_limit, tuple):
             weight_limit = (1, weight_limit)
+        weight_gen = kwargs.get("weight_gen",lambda:random.randint(weight_limit[0],weight_limit[1]))
 
         if not 0 <= chain <= 1 or not 0 <= flower <= 1:
             raise Exception("chain and flower must be between 0 and 1")
@@ -83,15 +84,15 @@ def tree(point_count, chain=0, flower=0, **kwargs):
         random_count = point_count - 1 - chain_count - flower_count
 
         for i in range(2, chain_count+2):
-            weight = random.randint(weight_limit[0], weight_limit[1])
+            weight = weight_gen()
             graph.add_edge(i-1, i, weight=weight)
 
         for i in range(chain_count+2, chain_count+flower_count+2):
-            weight = random.randint(weight_limit[0], weight_limit[1])
+            weight = weight_gen()
             graph.add_edge(1, i, weight=weight)
 
         for i in range(point_count-random_count+1, point_count+1):
-            weight = random.randint(weight_limit[0], weight_limit[1])
+            weight = weight_gen()
             u = random.randrange(1, i)
             graph.add_edge(u, i, weight=weight)
 
@@ -103,6 +104,7 @@ def binary_tree(point_count, left=0, right=0, **kwargs):
         weight_limit = kwargs.get("weight_limit", (1, 1))
         if not isinstance(weight_limit, tuple):
             weight_limit = (1, weight_limit)
+        weight_gen = kwargs.get("weight_gen",lambda:random.randint(weight_limit[0],weight_limit[1]))
 
         if not 0 <= left <= 1 or not 0 <= right <= 1:
             raise Exception("left and right must be between 0 and 1")
@@ -114,7 +116,7 @@ def binary_tree(point_count, left=0, right=0, **kwargs):
         graph = Graph(point_count,directed)
         for i in range(2, point_count+1):
             edge_pos = random.uniform(0, 1)
-            weight = random.randint(weight_limit[0], weight_limit[1])
+            weight = weight_gen()
 
             node = 0
             if edge_pos < left or left+right < edge_pos <= (1.0-left-right)/2: # Left
@@ -132,16 +134,43 @@ def binary_tree(point_count, left=0, right=0, **kwargs):
 
     @staticmethod
     def graph(point_count, edge_count, **kwargs):
-        directed = kwargs.get("directed", True)
+        directed = kwargs.get("directed", False)
         weight_limit = kwargs.get("weight_limit", (1,1))
         if not isinstance(weight_limit, tuple):
             weight_limit = (1, weight_limit)
-
-        graph = Graph(point_count)
+        weight_gen = kwargs.get("weight_gen",lambda:random.randint(weight_limit[0],weight_limit[1]))
+        graph = Graph(point_count,directed)
         for i in range(edge_count):
             u = random.randint(1, point_count)
             v = random.randint(1, point_count)
-            weight = random.randint(weight_limit[0], weight_limit[1])
-            graph.add_edge(u, v, weight=weight, directed=directed)
+            weight = weight_gen()
+            graph.add_edge(u, v, weight=weight)
+        return graph
 
+    #hack spfa (maybe?)
+    @staticmethod
+    def hack_spfa(point_count, **kwargs):
+        directed = kwargs.get("directed", False)
+        extraedg = kwargs.get("extra_edge", 2)
+        weight_limit = kwargs.get("weight_limit", (1,1))
+        if not isinstance(weight_limit, tuple):
+            weight_limit = (1, weight_limit)
+        weight_gen = kwargs.get("weight_gen",lambda:random.randint(weight_limit[0],weight_limit[1]))
+        skp=point_count+3
+        graph=Graph(point_count,directed)
+        if point_count%2==1:
+            skp=point_count/2+1
+        half=point_count/2
+        for i in range(1,half):
+            (x,y) = (i,i+1)
+            graph.add_edge(x+(x>=skp), y+(y>=skp), weight=weight_gen())
+            (x,y) = (i+half,i+half+1)
+            graph.add_edge(x+(x>=skp), y+(y>=skp), weight=weight_gen())
+        for i in range(1,half+1):
+            (x,y) = (i,i+half)
+            graph.add_edge(x+(x>=skp), y+(y>=skp), weight=weight_gen())
+        for i in range(extraedg):
+            u = random.randint(1, point_count)
+            v = random.randint(1, point_count)
+            graph.add_edge(u, v, weight=weight_gen())
         return graph
diff --git a/test2.py b/test2.py
index 314694d..2f7ed5c 100644
--- a/test2.py
+++ b/test2.py
@@ -3,18 +3,14 @@
 from cyaron import *
 
 _n = ati([0, 7, 50])
-_m = ati([0, 11, 100])
 
 def oper(x):
-  return "%d %d" % (x.start, x.end)
+    return "%d %d" % (x.start, x.end)
 
 for i in range(1, 3):
     test_data = IO(file_prefix="test", data_id=i)
     n = _n[i]
-    m = _m[i]
-    s = randint(1, n)
-    t = randint(1, n)
-    test_data.writeln(n, m, s, t)
+    test_data.writeln(n)
     graph = Graph.tree(n,0.3,0.3)
     test_data.writeln(graph.to_str(output=oper))
     test_data.writeln('============Shuffle============')
diff --git a/test3.py b/test3.py
new file mode 100644
index 0000000..65f79b6
--- /dev/null
+++ b/test3.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+
+from cyaron import *
+import random
+
+_n = ati([0, 7, 8])
+
+def oper(x):
+    return "%d %d  weight=%d,%d" % (x.start, x.end, x.weight[0], x.weight[1])
+
+def wg():
+    return [random.randint(3,5),random.randint(1,10)]
+
+for i in range(1, 3):
+    test_data = IO(file_prefix="test", data_id=i)
+    n = _n[i]
+    test_data.writeln(n)
+    graph = Graph.hack_spfa(n,weight_gen=wg)
+    test_data.writeln(graph.to_str(output=oper))
+    test_data.writeln('============Shuffle============')
+    test_data.writeln(graph.to_str(output=oper,shuffle=True))
+    test_data.output_gen("~/Downloads/std_binary")
+    # A binary file or shell command that accepts input from stdin and outputs to stdout