leetcode做题总结，题目Clone Graph 133

最新推荐文章于 2022-02-23 10:37:52 发布

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本文详细介绍了如何使用广度优先搜索算法和哈希映射来克隆一个图结构，通过构建映射关系确保了图中每个节点的正确复制，并维护了节点之间的连接关系。

题目是复制一个图，方法是使用广度优先历遍，然后使用HASHMAP判断重复然后放入队列。像这种clone或者两者比较的题目有个好的方法是使用map使他们之间建立映射。

public class Solution {
    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
        if(node == null)
            return null;
 
        Queue<UndirectedGraphNode> queue = new LinkedList<UndirectedGraphNode>();
        HashMap<UndirectedGraphNode, UndirectedGraphNode> map = 
                                   new HashMap<UndirectedGraphNode,UndirectedGraphNode>();
 
        UndirectedGraphNode newHead = new UndirectedGraphNode(node.label);
 
        queue.offer(node);
        map.put(node, newHead);
 
        while(!queue.isEmpty()){
            UndirectedGraphNode curr = queue.poll();
            //List<UndirectedGraphNode> currNeighbors = curr.neighbors; 
 
            for(UndirectedGraphNode aNeighbor: curr.neighbors){
                if(!map.containsKey(aNeighbor)){
                    UndirectedGraphNode copy = new UndirectedGraphNode(aNeighbor.label);
                    map.put(aNeighbor,copy);
                    map.get(curr).neighbors.add(copy);
                    queue.add(aNeighbor);
                }else{
                    map.get(curr).neighbors.add(map.get(aNeighbor));
                }
            }
 
        }
        return newHead;
    }
}