删除排序链表中的重复元素
单指针法
//一个指针往后遍历
class Solution {
public:
ListNode* deleteDuplicates(ListNode* head) {
if(!head || !head->next)
{
return head;
}
ListNode* tempnode = head;//这个头结点里面好像有元素
while(tempnode->next)
{
if(tempnode->val == tempnode->next->val)
{
tempnode->next = tempnode->next->next;
}
else
{
tempnode = tempnode->next;
}
}
return head;
}
};
双指针-前后指针法
注意前后指针的链接
class Solution {
public:
ListNode* deleteDuplicates(ListNode* head) {
if(!head || !head->next)
{
return head;
}
ListNode* Prev = head;
ListNode* Next = head->next;
while(Next)
{
if(Prev->val == Next->val)
{
Prev->next = Next->next;
Next = Next->next;
}
else
{
Prev= Next;
Next = Next->next;
}
}
return head;
}
};
递归法
感谢这位老哥的分享——链接
class Solution {
public:
ListNode* deleteDuplicates(ListNode* head) {
if(!head || !head->next)
{
return head;
}
head->next = deleteDuplicates(head->next);
if(head->val == head->next->val)
{
head = head->next;
}
return head;
}
};
图解:
