138. 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.
struct RandomListNode {
int label;
RandomListNode *next, *random;
RandomListNode(int x) : label(x), next(NULL), random(NULL) {}
};
class Solution_138_1 {
public:
RandomListNode * copyRandomList(RandomListNode *head) {
//新节点插入到旧节点后面
for (RandomListNode* cur = head; cur != nullptr; ) {
RandomListNode* node = new RandomListNode(cur->label);
node->next = cur->next;
cur->next = node;
cur = node->next;
}
//复制random指针指向
for (RandomListNode* cur = head; cur != nullptr; ) {
if (cur->random != NULL)
cur->next->random = cur->random->next;
cur = cur->next->next;
}
// 分拆两个链表
RandomListNode dummy(-1);
for (RandomListNode* cur = head, *new_cur = &dummy;
cur != nullptr; ) {
//先更新new_cur
new_cur->next = cur->next;
new_cur = new_cur->next;
//再处理旧节点
cur->next = new_cur->next;
cur = cur->next;
}
return dummy.next;
}
};
三次for循环示意图：
第一遍遍历，在原节点后面创建一个新节点，
第二遍遍历，复制新节点间的random关系指向
第三步，分离两个链表。