- 输入一个复杂链表(每个节点中有节点值,以及两个指针,一个指向下一个节点,另一个特殊指针指向任意一个节点),返回结果为复制后复杂链表的head。(注意,输出结果中请不要返回参数中的节点引用,否则判题程序会直接返回空)
- 下面的思路来自《剑指offer》,使用分治法,将整个任务分成几个步骤完成,复杂问题简单化。
总共分为三步,每个步骤可以单独封装成一个函数完成:
- 遍历链表,复制每个结点,如复制结点
A
得到A1
,将结点A1
插到结点A
后面; - 重新遍历链表,复制老结点的随机指针给新结点,如
A1.random = A.random.next
; - 拆分链表,将链表拆分为原链表和复制后的链表。
详细流程及图示:
- 遍历链表,复制每个结点,如复制结点
A
得到A1
,将结点A1
插到结点A
后面;
- 重新遍历链表,复制老结点的随机指针给新结点,如
A1.random = A.random.next
;
- 拆分链表,将链表拆分为原链表和复制后的链表。
- 递归,简单,思路清晰
/*
struct RandomListNode {
int label;
struct RandomListNode *next, *random;
RandomListNode(int x) :
label(x), next(NULL), random(NULL) {
}
};
*/
class Solution {
private:
void CloneNodes(RandomListNode* pHead){
if(pHead==NULL) return;
RandomListNode* pTemp = new RandomListNode(pHead->label);
pTemp->next = pHead->next;
pHead->next = pTemp;
CloneNodes(pTemp->next);
}
void ConnectRandomNode(RandomListNode* pHead){
if(pHead==NULL) return;
if(pHead->random){
pHead->next->random = pHead->random->next;
}
ConnectRandomNode(pHead->next->next);
}
RandomListNode* SplitList(RandomListNode* pHead){
if(pHead==NULL) return NULL;
RandomListNode* pNewHead = pHead->next;
pHead->next = pNewHead->next;
if(pNewHead->next){
pNewHead->next = pNewHead->next->next;
}
SplitList(pHead->next);
return pNewHead;
}
public:
RandomListNode* Clone(RandomListNode* pHead)
{
CloneNodes(pHead);
ConnectRandomNode(pHead);
return SplitList(pHead);
}
};
- 迭代
/*
struct RandomListNode {
int label;
struct RandomListNode *next, *random;
RandomListNode(int x) :
label(x), next(NULL), random(NULL) {
}
};
*/
class Solution {
private:
void CloneNodes(RandomListNode* pHead){
while(pHead){
RandomListNode* pTemp = new RandomListNode(pHead->label);
pTemp->next = pHead->next;
pHead->next = pTemp;
pHead = pTemp->next;
}
}
void ConnectRandomNode(RandomListNode* pHead){
while(pHead){
if(pHead->random){
pHead->next->random = pHead->random->next;
}
pHead = pHead->next->next;
}
}
RandomListNode* SplitList(RandomListNode* pHead){
if(pHead==NULL) return NULL;
RandomListNode* pNewHead = pHead->next;
while(pHead){
RandomListNode* pNewListNode = pHead->next;
pHead->next = pNewListNode->next;
if(pNewListNode->next){
pNewListNode->next = pNewListNode->next->next;
}
pHead = pHead->next;
}
return pNewHead;
}
public:
RandomListNode* Clone(RandomListNode* pHead)
{
CloneNodes(pHead);
ConnectRandomNode(pHead);
return SplitList(pHead);
}
};