19.py

# Python3 program to print DFS traversal
# from a given  graph
from collections import defaultdict
 
# This class represents a directed graph using
# adjacency list representation
 
 
class Graph:
 
    # Constructor
    def __init__(self):
 
        # default dictionary to store graph
        self.graph = defaultdict(list)
 
    # function to add an edge to graph
    def addEdge(self, u, v):
        self.graph[u].append(v)
 
    # A function used by DFS
    def DFSUtil(self, v, visited):
 
        # Mark the current node as visited
        # and print it
        visited.add(v)
        print(v, end=' ')
 
        # Recur for all the vertices
        # adjacent to this vertex
        for neighbour in self.graph[v]:
            if neighbour not in visited:
                self.DFSUtil(neighbour, visited)
 
    # The function to do DFS traversal. It uses
    # recursive DFSUtil()
    def DFS(self, v):
 
        # Create a set to store visited vertices
        visited = set()
 
        # Call the recursive helper function
        # to print DFS traversal
        self.DFSUtil(v, visited)
 
# Driver's code
 
 
# Create a graph given
# in the above diagram
if __name__ == "__main__":
    g = Graph()
    g.addEdge(0, 1)
    g.addEdge(0, 2)
    g.addEdge(1, 2)
    g.addEdge(2, 0)
    g.addEdge(2, 3)
    g.addEdge(3, 3)
 
    print("Following is DFS from (starting from vertex 2)")
    # Function call
    g.DFS(0)
 
# This code is contributed by Neelam Yadav

           

# sol=Solution()
     
# # nums = [-1,-1,-1,0,1,1]
# nums = [2,1,-1]
# # nums = [-1,-1,-1,-1,-1,0]
# # print(bits[-10:])
# res = sol.pivotIndex(nums)
# print(res)

# # print(-1//2)
# # a = 5
# # ~a  #-2
# # print(~a)
# # b = 15
# # ~b  #-16
# # print(~b)