data_structures_task.py

import networkx as nx
import matplotlib.pyplot as plt
from collections import defaultdict

class Graph:
    def __init__(self, vertices):
        self.graph = defaultdict(list)
        self.V = vertices
        self.nx_graph = nx.DiGraph()

    def add_edge(self, u, v):
        self.graph[u].append(v)
        self.nx_graph.add_edge(u, v)

    def draw_graph(self, layout='circular'):
        if layout == 'circular':
            pos = nx.circular_layout(self.nx_graph)
        elif layout == 'kamada_kawai':
            pos = nx.kamada_kawai_layout(self.nx_graph)
        elif layout == 'spring':
            pos = nx.spring_layout(self.nx_graph)
        else:
            raise ValueError("Invalid layout parameter. Choose from 'circular', 'kamada_kawai', or 'spring'.")
        
        nx.draw(self.nx_graph, pos, with_labels=True, node_color='lightblue', font_weight='bold', arrows=True, node_size=2000)
        plt.show()

    def dfs(self, v, visited, stack):
        visited[v] = True
        for i in self.graph[v]:
            if not visited[i]:
                self.dfs(i, visited, stack)
        stack.append(v)

    def topological_sort(self):
        visited = [False] * self.V
        stack = []

        for i in range(self.V):
            if not visited[i]:
                self.dfs(i, visited, stack)

        return stack[::-1]

# Test the implementation
g = Graph(6)
g.add_edge(5, 2)
g.add_edge(5, 0)
g.add_edge(4, 0)
g.add_edge(4, 1)
g.add_edge(2, 3)
g.add_edge(3, 1)

print("Graph Visualization (Circular layout):")
g.draw_graph(layout='circular')

print("Graph Visualization (Kamada-Kawai layout):")
g.draw_graph(layout='kamada_kawai')

print("Graph Visualization (Spring layout):")
g.draw_graph(layout='spring')

print("\nTopological Sort:")
print(g.topological_sort())