LeetCode 138. Copy List with Random Pointer

题目描述:

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.

解题思路：

我也不记得这道题在哪里看到过， 基本思路就是在原链表上复制每一个节点， 到原来节点的后面， 然后修复random pointers， 最后再将复制出来的节点， 从原链表中分离出来。



代码如下：

class Solution {
public:
RandomListNode *copyRandomList(RandomListNode *head) {
// 为每一个节点做一个备份， 插入原链表
RandomListNode *pcur = head;
while (pcur){
RandomListNode * newNode = new RandomListNode(pcur->label);
newNode->next = pcur->next;
pcur->next = newNode;
pcur = pcur->next->next;
}

// 复制random pointers
pcur = head;
while (pcur){
RandomListNode * pNext = pcur->next;
if (pcur->random)
pNext->random = pcur->random->next;
pcur = pcur->next->next;
}

// 分割链表
RandomListNode myhead(0);
RandomListNode * pre = &myhead;
pcur = head;
while (pcur){
RandomListNode * pNext = pcur->next;
pcur->next = pNext->next;
pcur = pcur->next;
pre->next = pNext;
pNext->next = nullptr;
pre = pre->next;
}

return myhead.next;
}
};