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clone-graph.py
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clone-graph.py
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# Time: O(n)
# Space: O(n)
#
# Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.
#
#
# OJ's undirected graph serialization:
# Nodes are labeled uniquely.
#
# We use # as a separator for each node, and , as a separator for node label and each neighbor of the node.
# As an example, consider the serialized graph {0,1,2#1,2#2,2}.
#
# The graph has a total of three nodes, and therefore contains three parts as separated by #.
#
# First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
# Second node is labeled as 1. Connect node 1 to node 2.
# Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.
# Visually, the graph looks like the following:
#
# 1
# / \
# / \
# 0 --- 2
# / \
# \_/
#
# Definition for a undirected graph node
class UndirectedGraphNode:
def __init__(self, x):
self.label = x
self.neighbors = []
class Solution:
# @param node, a undirected graph node
# @return a undirected graph node
def cloneGraph(self, node):
if node is None:
return None
cloned_node = UndirectedGraphNode(node.label)
cloned, queue = {node:cloned_node}, [node]
while queue:
current = queue.pop()
for neighbor in current.neighbors:
if neighbor not in cloned:
queue.append(neighbor)
cloned_neighbor = UndirectedGraphNode(neighbor.label)
cloned[neighbor] = cloned_neighbor
cloned[current].neighbors.append(cloned[neighbor])
return cloned[node]