Copy List with Random Pointer

A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.

Return a deep copy of the list.

 

/**
 * Definition for singly-linked list with a random pointer.
 * class RandomListNode {
 *     int label;
 *     RandomListNode next, random;
 *     RandomListNode(int x) { this.label = x; }
 * };
 */
public class Solution {
    public RandomListNode copyRandomList(RandomListNode head) {
        if (head == null) {
        	return null;
        }
        RandomListNode cur = head;
        RandomListNode next = null;
        while (cur != null) {
        	next = cur.next;
        	cur.next = new RandomListNode(cur.label);
        	cur.next.next = next;
        	cur = next;
        }
        cur = head;
        RandomListNode copy = null;
        while (cur != null) {
        	next = cur.next.next;
        	copy = cur.next;
        	copy.random = cur.random != null ? cur.random.next : null;
        	cur = next;
        }
        RandomListNode res = head.next;
        cur = head;
        while (cur != null) {
        	next = cur.next.next;
        	copy = cur.next;
        	cur.next = next;
        	copy.next = next != null ? next.next : null;
        	cur = next;
        }
        return res;
    }
}