力扣labuladong——一刷day53

提示：文章写完后，目录可以自动生成，如何生成可参考右边的帮助文档

文章目录

前言
[一、力扣1485. 克隆含随机指针的二叉树](#一、力扣1485. 克隆含随机指针的二叉树)
[二、力扣1490. 克隆 N 叉树](#二、力扣1490. 克隆 N 叉树)
[三、力扣133. 克隆图](#三、力扣133. 克隆图)
[四、力扣138. 随机链表的复制](#四、力扣138. 随机链表的复制)

前言

复制带有随机指针的二叉树或者链表，或者图，先设置一个map作为映射，原节点与复制后节点的映射，然后正常的遍历返回节点，但需要注意的是，遍历顺序，先遍历其他节点，最后遍历随机节点，因为随机节点可能没有被创建，遍历其他节点时，创建复制节点，遍历随机节点时，查找映射关系返回

一、力扣1485. 克隆含随机指针的二叉树

java 复制代码

/**
 * Definition for Node.
 * public class Node {
 *     int val;
 *     Node left;
 *     Node right;
 *     Node random;
 *     Node() {}
 *     Node(int val) { this.val = val; }
 *     Node(int val, Node left, Node right, Node random) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *         this.random = random;
 *     }
 * }
 */

class Solution {
    HashMap<Node,NodeCopy> map = new HashMap<>();
    public NodeCopy copyRandomBinaryTree(Node root) {
        if(root == null){
            return null;
        }
        if(map.containsKey(root)){
            return map.get(root);
        }
        NodeCopy cur = new NodeCopy(root.val);
        map.put(root,cur);
        cur.left = copyRandomBinaryTree(root.left);
        cur.right = copyRandomBinaryTree(root.right);
        cur.random = copyRandomBinaryTree(root.random);
        return cur;
    }
}

二、力扣1490. 克隆 N 叉树

java 复制代码

/*
// Definition for a Node.
class Node {
    public int val;
    public List<Node> children;

    
    public Node() {
        children = new ArrayList<Node>();
    }
    
    public Node(int _val) {
        val = _val;
        children = new ArrayList<Node>();
    }
    
    public Node(int _val,ArrayList<Node> _children) {
        val = _val;
        children = _children;
    }
};
*/

class Solution {
    public Node cloneTree(Node root) {
        if(root == null){
            return null;
        }
        Node cur = new Node(root.val);
        cur.children = new LinkedList<Node>();
        for(Node n : root.children){
            Node c = cloneTree(n);
            cur.children.add(c);
        }
        return cur;
    }
}

三、力扣133. 克隆图

java 复制代码

/*
// Definition for a Node.
class Node {
    public int val;
    public List<Node> neighbors;
    public Node() {
        val = 0;
        neighbors = new ArrayList<Node>();
    }
    public Node(int _val) {
        val = _val;
        neighbors = new ArrayList<Node>();
    }
    public Node(int _val, ArrayList<Node> _neighbors) {
        val = _val;
        neighbors = _neighbors;
    }
}
*/

class Solution {
    HashSet<Node> visited = new HashSet<>();
    Map<Node,Node> originToClone = new HashMap<>();
    public Node cloneGraph(Node node) {
        traverse(node);
        return originToClone.get(node);
    }
    void traverse(Node node){
        if(node == null){
            return;
        }
        if(visited.contains(node)){
            return;
        }
        visited.add(node);
        originToClone.put(node,new Node(node.val));
        Node copyNode = originToClone.get(node);
        for(Node n : node.neighbors){
            traverse(n);
            copyNode.neighbors.add(originToClone.get(n));
        }
    }
}

四、力扣138. 随机链表的复制

java 复制代码

/*
// 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 {
    Map<Node , Node> map = new HashMap<>();
    public Node copyRandomList(Node head) {
        if(head == null){
            return null;
        }
        if(map.containsKey(head)){
            return map.get(head);
        }
        Node cur = new Node(head.val);
        map.put(head,cur);
        cur.next = copyRandomList(head.next);
        cur.random = copyRandomList(head.random);
        return cur;
    }
}