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.
第一遍扫的时候巧妙运用next指针, 开始数组是1->2->3->4。
然后扫描过程中 先建立copy节点 1->1`->2->2`->3->3`->4->4`,
然后第二遍copy的时候去建立边的copy, 拆分节点, 一边扫描一边拆成两个链表,
这里用到两个dummy node。第一个链表变回 1->2->3 , 然后第二变成 1`->2`->3`
I believe now points to the "newly" created node, i.e. the copy, not the original node, which is later removed.
Need deep copy, which means a new node to be created.
private void copyNext(RandomListNode head) {
while (head != null) {
RandomListNode newNode = new RandomListNode(head.label);
newNode.next = head.next;
newNode.random = head.random;
head.next = newNode;
head = head.next.next;
}
}
private void copyRandom(RandomListNode head) {
while (head != null) {
if (head.next.random != null) {
head.next.random = head.random.next;
}
head = head.next.next;
}
}
private RandomListNode splitList(RandomListNode head) {
RandomListNode newHead = head.next;
while (head != null) {
RandomListNode temp = head.next;
head.next = temp.next;
if (temp.next != null) {
temp.next = temp.next.next;
}
head = head.next;
}
return newHead;
}
public RandomListNode copyRandomList(RandomListNode head) {
if (head == null) {
return head;
}
copyNext(head);
copyRandom(head);
return splitList(head);
}