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from collections import defaultdict
class Graph:
def __init__(self):
self.graph = defaultdict(list)
def addEdge(self, u, v):
self.graph[u].append(v)
print("This is u" , u)
def DFSUtil(self, v, visited):
visited.add(v)
print(v, end=" ")
for neighbor in self.graph[v]:
if neighbor not in visited:
self.DFSUtil(neighbor, visited)
def DFS(self, v):
visited = set()
self.DFSUtil(v, visited)
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("It's done")
g.DFS(2)
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# left to right, pre-order depth first tree search, iterative. O(n) time/space
def depthFirstSearch(root):
st = [root]
while st:
current = st.pop()
print(current)
if current.right: st.append(current.right)
if current.left: st.append(current.left)
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# left to right, pre-order depth first tree search, recursive. O(n) time/space
def depthFirstSearchRec(root):
if root == None: return
print(root)
depthFirstSearch(root.left)
depthFirstSearch(root.right)