Linked list pointer 138. The copy with Random
Given a list, each node contains a random additional pointer that can point to any node in the linked list node or empty.
The requirement to return a deep copy of the list.
We use a linked list of n nodes to the input / output in a linked list. Each node with a [val, random_index] represents:
val: a Node.val integer representation.
random_index: random pointer node index (ranging from 0 to n-1); if you do not point to any node, was null.
Example 1:
Input: head = [[7, null ], [13,0], [11,4], [10,2], [1,0]]
Output: [[7, null], [13,0], [11,4], [10, 2], [1,0]]
example 2:
Input: head = [[1,1], [2,1]]
Output: [[1,1], [2,1]]
Example 3:
Input: head = [[3, null ], [3,0], [3, null]]
Output: [[3, null], [3,0], [3, null]]
Example 4:
Input: head = []
Output: []
Explanation: the given list is empty (null pointer), and therefore returns null.
prompt:
-10000 <= Node.val <= 10000
Node.random node in the linked list is empty (null) or point.
The number of nodes does not exceed 1000.
/*
// 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 {
public Node copyRandomList(Node head) {
if(head == null){
return head;
}
// 空间复杂度O(1)，将克隆结点放在原结点后面
Node node = head;
// 1->2->3 ==> 1->1'->2->2'->3->3'
while(node != null){
Node clone = new Node(node.val,node.next,null);
Node temp = node.next;
node.next = clone;
node = temp;
}
// 处理random指针
node = head;
while(node != null){
// ！！
node.next.random = node.random == null ? null : node.random.next;
node = node.next.next;
}
// 还原原始链表，即分离原链表和克隆链表
node = head;
Node cloneHead = head.next;
while(node.next != null){
Node temp = node.next;
node.next = node.next.next;
node = temp;
}
return cloneHead;
}
}
