35. 复杂链表的复制

/*
// Definition for a Node.
class Node {
    int val;
    Node next;
    Node random;

    public Node(int val) {
        this.val = val;
        this.next = null;
        this.random = null;
    }
}
*/

class Solution {
    public Node copyRandomList(Node head) {
        if(head == null) return head;
        copyNext(head);
        copyRandom(head);
        return link(head);
    }
    private void copyNext(Node head){
        while(head != null){
            Node copyNode = new Node(head.val);
            Node nextNode = head.next;
            copyNode.next = nextNode;
            head.next = copyNode;
            
            head = nextNode;
        }
    }
    
    private void copyRandom(Node node){
        while(node != null){
            Node copyNode = node.next;
            if(node.random != null){
                Node rnode = node.random;
                //
                copyNode.random = rnode.next;
            }
            node = copyNode.next;
        }  
    }
    
    private Node link(Node head){
        Node copyNode = head.next;
        Node copyHead = copyNode;
        head.next = copyNode.next;
        head = head.next;
        
        while(head != null){
            //将连接断开
            copyNode.next = head.next;
            head.next = head.next.next;
            head = head.next;   
            copyNode = copyNode.next;
        }
        return copyHead;
    }
    
}