图

一 克隆图

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133 Clone Graph

    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
        if (node == null) return node;
        LinkedList<UndirectedGraphNode> queue = new LinkedList<>();
        HashMap<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>();
        queue.offer(node);
        UndirectedGraphNode copy = new UndirectedGraphNode(node.label);
        map.put(node, copy);
        while (!queue.isEmpty()){
            UndirectedGraphNode cur = queue.poll();
            for (int i = 0; i < cur.neighbors.size(); i++){
                if (!map.containsKey(cur.neighbors.get(i))){
                    copy = new UndirectedGraphNode(cur.neighbors.get(i).label);
                    map.put(cur.neighbors.get(i), copy);
                    queue.offer(cur.neighbors.get(i));
                }
                map.get(cur).neighbors.add(map.get(cur.neighbors.get(i)));
            }
        }
        return map.get(node);
    }

    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
        if (node == null) return node;
        LinkedList<UndirectedGraphNode> stack = new LinkedList<>();
        HashMap<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>();
        stack.push(node);
        UndirectedGraphNode copy = new UndirectedGraphNode(node.label);
        map.put(node, copy);
        while (!stack.isEmpty()){
            UndirectedGraphNode cur = stack.poll();
            for (int i = 0; i < cur.neighbors.size(); i++){
                if(!map.containsKey(cur.neighbors.get(i))){
                    copy = new UndirectedGraphNode(cur.neighbors.get(i).label);
                    map.put(cur.neighbors.get(i), copy);
                    stack.push(cur.neighbors.get(i));
                }
                map.get(cur).neighbors.add(map.get(cur.neighbors.get(i)));  
            }
            
        }
        return map.get(node);
    }

    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {  
        if(node == null)  
            return null;  
        HashMap<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<UndirectedGraphNode, UndirectedGraphNode>();  
        UndirectedGraphNode copy = new UndirectedGraphNode(node.label);  
        map.put(node,copy);  
        helper(node,map);  
        return copy;  
    }  
    private void helper(UndirectedGraphNode node, HashMap<UndirectedGraphNode, UndirectedGraphNode> map)  
    {  
        for(int i=0;i<node.neighbors.size();i++)  
        {   
            UndirectedGraphNode cur = node.neighbors.get(i);  
            if(!map.containsKey(cur))  
            {  
                UndirectedGraphNode copy = new UndirectedGraphNode(cur.label);  
                map.put(cur,copy);  
                helper(cur,map);  
            }  
            map.get(node).neighbors.add(map.get(cur));  
        }  
    }