Clone Graph--leetcode

Source: Internet
Author: User

Clone an undirected graph. Each node in the graph contains a and label a lists of its neighbors .

OJ ' s undirected graph serialization:

Nodes is 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 # .

    1. First node is labeled as 0 . Connect node to 0 both nodes 1 and 2 .
    2. Second node is labeled as 1 . Connect node to 1 node 2 .
    3. 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         /          \_/

The main idea of the topic is given an image without a direction, there may be a ring, a method of realization, deep clone of this figure.

My approach is to use BFS, starting at a point, traversing its neighbors, then joining the queue, when the queue is non-empty, looping through, because the label is unique, using a map to save the newly generated node, using the label as key. In addition, the visited array is used to save the queue to avoid repeated traversal.

Talk is cheap>>

 PublicUndirectedgraphnode clonegraph (undirectedgraphnode root) {HashSet<Integer> visited =NewHashset<>(); if(root==NULL)            return NULL; List<UndirectedGraphNode> queue =NewArraylist<>(); HashMap<Integer,UndirectedGraphNode> map =NewHashmap<>();        Queue.add (root);  while(!Queue.isempty ()) {undirectedgraphnode node= Queue.get (0); if(Map.get (node.label) = =NULL) {map.put (Node.label,NewUndirectedgraphnode (Node.label)); } undirectedgraphnode tmp=Map.get (Node.label); Queue.remove (0);  for(inti = 0; I < node.neighbors.size (); i++) {                intKey =Node.neighbors.get (i). label; if(Map.get (key) = =NULL) {map.put (key,NewUndirectedgraphnode (key));                } tmp.neighbors.add (Map.get (key));                Visited.add (Node.label); if(!Visited.contains (Key))                    {Queue.add (Node.neighbors.get (i));                Visited.add (key); }            }        }        returnMap.get (Root.label); }

Clone Graph--leetcode

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