update readme & bug fix

Author: nik1as

README.md

@@ -1,8 +1,19 @@
 # Visualization of max flow algorithms
 
-implemented algorithms:
+## Implemented algorithms
 - Ford-Fulkerson
 - Edmonds-Karp
 - Capacity Scaling
 - Dinic
-- Goldberg-Tarjan
+- Goldberg-Tarjan/Preflow-Push
+
+
+# Usage
+install the requirements:
+```
+pip install -r requirements.txt
+```
+and execute the ``main`` file:
+```
+python3 main.py
+```

main.py

@@ -204,7 +204,7 @@ def render_goldberg_tarjan(self, edges, excess, label, node_id):
                                 outline="red", width=3)
 
         for edge in self.graph.get_base_edges():
-            color = "red" if edge in edges else "black"
+            color = "red" if edge in edges or edge.reverse_edge in edges else "black"
             self.render_edge(edge, color)
 
     def render_ford_fulkerson(self, edges):