[35] to prove safety offer. Replication complex list

Title Description

A complex input list (each node has a node value, and two pointers, one pointing to the next node, a special pointer to any other node), returns a value after the head of the list replication complex. (Note that the output results do not return parameter node reference, otherwise the program will return empty sentenced questions directly)

Thinking

Two programs

• hashMap fast copy, the space complexity of O (N)
• Copying the original node in the list, and split

Code

import java.util.HashMap;

public class Offer35_Clone {

    // 定义复杂链表
    public static class RandomNode{
        int val;
        RandomNode next;
        RandomNode random;

        RandomNode(int data){
            this.val = data;
        }
    }

    // 1.hash解决方案
    public RandomNode clone(RandomNode head){
        if(head == null) return null;
        // 构建一个hashMap，key为Node，value为Node的复制值
        HashMap<RandomNode, RandomNode> hash = new HashMap<>();
        RandomNode cur = head;
        while(cur != null){
            hash.put(cur, new RandomNode(cur.val));
            cur = cur.next;
        }

        // 给每个复制的结点赋值next和random指针
        cur = head;
        while(cur != null){
            hash.get(cur).next = hash.get(cur.next);
            hash.get(cur).random = hash.get(cur.random);
            cur = cur.next;
        }

        return hash.get(head);
    }

    public static RandomNode copy2(RandomNode head){
        if(head == null) return null;

        // 在原链表的每个结点后面复制一个结点并连接成新链表
        RandomNode cur = head;
        RandomNode next = null;

        while(cur != null){
            next = cur.next;
            cur.next = new RandomNode(cur.val);
            cur.next.next = next;
            cur = next;
        }

        // 对复制结点设置random指针，指向当前复制结点前一个结点的random指针的下一个节点
        cur  = head;
        RandomNode curCopy = null;
        while(cur != null){
            next = cur.next.next;
            curCopy = cur.next;
            curCopy.random = cur.random != null ? cur.random.next: null;
            cur = next;
        }

        // 分离
        RandomNode res = head.next;
        cur = head;
        while(cur != null){
            next = cur.next.next;
            curCopy = cur.next;
            curCopy.next = next != null ? next.next: null;
            cur = next;
        }
        return res;
    }
}