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  • Clone Graph

    题目

    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 #.

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

    方法

    主要分两步:第一步创建全部的结点。第二步,创建结点的neighbors
    /**
     * Definition for undirected graph.
     * class UndirectedGraphNode {
     *     int label;
     *     List<UndirectedGraphNode> neighbors;
     *     UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }
     * };
     */
    public class Solution {
        public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
        	if (node == null) {
        		return null;
        	}
        	Map<Integer, UndirectedGraphNode> map = new HashMap<Integer, UndirectedGraphNode>();
        	Map<Integer, UndirectedGraphNode> graph = new HashMap<Integer, UndirectedGraphNode>();
        	Queue<UndirectedGraphNode> queue = new LinkedList<UndirectedGraphNode>();
        	queue.offer(node);
        	while(!queue.isEmpty()) {
        		UndirectedGraphNode temp = queue.poll();
        		
        		if (!map.containsKey(temp.label)) {
        			UndirectedGraphNode newTemp = new UndirectedGraphNode(temp.label);
        			graph.put(temp.label, temp);
        			map.put(temp.label, newTemp);
        		}
        		
        		for (UndirectedGraphNode neighbor : temp.neighbors) {
        			if (!map.containsKey(neighbor.label)) {
        				queue.offer(neighbor);
        			}
        		}
        	}
        	for (int label : graph.keySet()) {
        		UndirectedGraphNode temp = graph.get(label);
        		UndirectedGraphNode cloneTemp = map.get(temp.label);
    			for (UndirectedGraphNode neighbor : temp.neighbors) {
    				cloneTemp.neighbors.add(map.get(neighbor.label));
    			}
        	}
        	return map.get(node.label);
        }
    }



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  • 原文地址:https://www.cnblogs.com/mengfanrong/p/5191341.html
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