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 copy = head;
        while (copy != null) {
        	RandomListNode node = new RandomListNode(copy.label);
        	node.next = copy.next;
        	copy.next = node;
        	copy = node.next;
        }
        copy = head;
        while (copy!=null && copy.next!=null) {
        	if (copy.random != null) {
        		copy.next.random = copy.random.next;
        	}
        	copy = copy.next.next;
        }
        copy = head;
        RandomListNode cur = copy.next;
        RandomListNode tmp = cur;
        while (copy!=null && tmp!=null) {
        	copy.next = tmp.next;
        	copy = copy.next;
        	if (tmp.next != null) {
        		tmp.next = tmp.next.next;
        	}
        	tmp = tmp.next;
        }
        return cur;
    }
}