Update app.py

app.py

@@ -23,7 +23,7 @@ sidebar_option = st.sidebar.radio("Select an option",
                                   "Drawing: Simple Path", "Drawing: Spectral Embedding", "Drawing: Traveling Salesman Problem",
                                   "Drawing: Weighted Graph", "3D Drawing: Animations of 3D Rotation", "3D Drawing: Basic Matplotlib",
                                   "Graph: DAG - Topological Layout", "Graph: Erdos Renyi", "Graph: Karate Club", "Graph: Minimum Spanning Tree",
-                                  "Graph: Triads"])
+                                  "Graph: Triads", "Algorithms: Cycle Detection"])
 
 # Helper function to draw and display graph
 def draw_graph(G, pos=None, title="Graph Visualization"):
@@ -31,6 +31,66 @@ def draw_graph(G, pos=None, title="Graph Visualization"):
     nx.draw(G, pos=pos, with_labels=True, node_color='lightblue', node_size=500, font_size=10, font_weight='bold')
     st.pyplot(plt)
 
+def plot_cycle_detection(graph):
+    # Draw the graph
+    pos = nx.spring_layout(graph, seed=8020)
+    nx.draw(graph, pos, with_labels=True, node_size=2000, node_color="lightblue")
+
+    # Find and highlight the cycle
+    try:
+        cycle = nx.find_cycle(graph, orientation="original")
+        st.write("Cycle Detected:", cycle)
+
+        # Highlight the cycle in red
+        nx.draw_networkx_edges(graph, pos, edgelist=cycle, edge_color="r", width=2)
+    except nx.NetworkXNoCycle:
+        st.write("No cycle detected")
+
+    # Display the graph
+    plt.title("Cycle Detection in Directed Graph")
+    plt.show()
+
+def algorithms_cycle_detection():
+    st.title("Algorithms: Cycle Detection")
+
+    # Option to choose between creating your own or using the default example
+    graph_mode = st.radio(
+        "Choose a Mode:",
+        ("Default Example", "Create Your Own"),
+        help="The default example shows a predefined graph, or you can create your own."
+    )
+
+    if graph_mode == "Default Example":
+        # Create a predefined graph with a cycle
+        G = nx.DiGraph([(1, 2), (2, 3), (3, 4), (4, 2), (3, 5), (3, 2), (1, 5)])
+        st.write("Default Graph: A simple directed graph with a cycle.")
+        plot_cycle_detection(G)
+
+    elif graph_mode == "Create Your Own":
+        st.write("### Create Your Own Graph")
+
+        # Input for creating custom graph
+        edges_input = st.text_area("Enter directed edges (e.g., (1, 2), (2, 3), (3, 4), (4, 2)):")
+
+        if st.button("Generate Graph"):
+            if edges_input:
+                try:
+                    # Parse the input edges
+                    edges = [tuple(map(int, edge.strip()[1:-1].split(","))) for edge in edges_input.split(",")]
+                    G = nx.DiGraph(edges)
+
+                    st.write("Custom Graph:", G.edges())
+                    plot_cycle_detection(G)
+
+                except Exception as e:
+                    st.error(f"Error creating the graph: {e}")
+            else:
+                st.error("Please enter valid directed edges.")
+
+# Display the corresponding page based on sidebar option
+if sidebar_option == "Algorithms: Cycle Detection":
+    algorithms_cycle_detection()
+
 def triads_graph():
     st.title("Graph: Triads")