- 1.刪除一個無頭單鏈表的非尾節點,時間複雜度爲O(1)
struct ListNode
{
int val;
ListNode *next;
ListNode(int x):val(x),next(NULL) { }
};
//節點的後一個節點賦值給要刪除的節點,再刪除這個後面的節點。
int DelNotTail(ListNode *delnode)
{
if(delnode == NULL)
return -1;
ListNode *pnext = delnode->next;
delnode->val = pnext->val;
delnode->next = pnext->next;
delete pnext;
return 0;
- 從尾到頭打印單鏈表
struct ListNode
{
int val;
ListNode *next;
ListNode(int x):val(x),next(NULL) { }
};
void Print(ListNode *phead)
{
if(phead == NULL)
return ;
Print(phead->next);
cout << phead->val <<endl;
}
- 複雜鏈表的複製
一個鏈表的每個節點,有一個指向next指針指向下一個節點,還有一個random指針指向這個鏈表中的一個隨機節點或者NULL,現在要求實現複製這個鏈表,返回複製後的新鏈表。
struct RandomListNode {
int label;
struct RandomListNode *next, *random;
RandomListNode(int x) :
label(x), next(NULL), random(NULL) {
}
};
RandomListNode* Clone(RandomListNode* pHead)
{
if(pHead == NULL)
return NULL;
//第一步:每一個節點的後面插入一個新的節點
RandomListNode *pcur = pHead;
while(pcur)
{
RandomListNode *pm = new RandomListNode(pcur->label);
pm->next = pcur->next;
pcur->next = pm;
pcur = pm->next;
}
//第二步:爲每一個新節點的隨機指針賦值
pcur = pHead;
while(pcur)
{
RandomListNode *pnext = pcur->next; //指向新的節點
if(pcur->random == NULL)
pnext->random = NULL;
else
pnext->random = pcur->random->next;
pcur = pnext->next;
}
//第三步:將新的鏈表拆下來
RandomListNode *ph = pHead->next;
RandomListNode *pold = pHead;
RandomListNode *pnew = ph;
while(pnew)
{
pold->next = pnew->next;
pold = pnew->next; //當pnew指向最後一個節點時,此時pold指向空了,
pnew->next = (pold == NULL? NULL:pold->next);
pnew = (pold == NULL? NULL:pold->next);
}
return ph;
}