Python/graphs/depth_first_search_2.py
Lewis Tian 4fa8c9d4b4
Update graphs/depth_first_search_2.py ()
- update naming style to snake_case
- add type hints
2020-10-29 08:35:31 +08:00

66 lines
1.6 KiB
Python

#!/usr/bin/python
""" Author: OMKAR PATHAK """
class Graph:
def __init__(self):
self.vertex = {}
# for printing the Graph vertices
def print_graph(self) -> None:
print(self.vertex)
for i in self.vertex:
print(i, " -> ", " -> ".join([str(j) for j in self.vertex[i]]))
# for adding the edge between two vertices
def add_edge(self, from_vertex: int, to_vertex: int) -> None:
# check if vertex is already present,
if from_vertex in self.vertex:
self.vertex[from_vertex].append(to_vertex)
else:
# else make a new vertex
self.vertex[from_vertex] = [to_vertex]
def dfs(self) -> None:
# visited array for storing already visited nodes
visited = [False] * len(self.vertex)
# call the recursive helper function
for i in range(len(self.vertex)):
if not visited[i]:
self.dfs_recursive(i, visited)
def dfs_recursive(self, start_vertex: int, visited: list) -> None:
# mark start vertex as visited
visited[start_vertex] = True
print(start_vertex, end=" ")
# Recur for all the vertices that are adjacent to this node
for i in self.vertex:
if not visited[i]:
self.dfs_recursive(i, visited)
if __name__ == "__main__":
g = Graph()
g.add_edge(0, 1)
g.add_edge(0, 2)
g.add_edge(1, 2)
g.add_edge(2, 0)
g.add_edge(2, 3)
g.add_edge(3, 3)
g.print_graph()
print("DFS:")
g.dfs()
# OUTPUT:
# 0 -> 1 -> 2
# 1 -> 2
# 2 -> 0 -> 3
# 3 -> 3
# DFS:
# 0 1 2 3