LeetCode:Remove Duplicates from Sorted List
Given a sorted linked list, delete all duplicates such that each element appear only once.
For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.
分析：和从数组中移除重复元素那一题一样的思想
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *deleteDuplicates(ListNode *head) {
// IMPORTANT: Please reset any member data you declared, as
// the same Solution instance will be reused for each test case.
if(head == NULL || head->next == NULL)return head;
ListNode *index = head, *p = head->next, *pre = head;
while(p != NULL)
{
if(p->val != pre->val)
{
index = index->next;
index->val = p->val;
}
pre = p;
p = p->next;
}
p = index->next;
index->next = NULL;
while(p != NULL)
{//销毁多余的节点
ListNode *tmp = p;
p = p->next;
delete tmp;
}
return head;
}
};
LeetCode:Remove Duplicates from Sorted List II
Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.
For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3. 本文地址
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *deleteDuplicates(ListNode *head) {
// IMPORTANT: Please reset any member data you declared, as
// the same Solution instance will be reused for each test case.
if(head == NULL)return head;
//为操作方便添加头结点
ListNode *addHead = new ListNode();
addHead->next = head;
//index 指向已经保存的最后一个节点
ListNode *index = addHead, *p = head;
while(p != NULL)
{
if(p->next == NULL || p->val != p->next->val)
{//当前节点没有重复
index = index->next;
index->val = p->val;
p = p->next;
}
else
{//当前节点有重复，找到当前节点的最后一个副本的下一个元素
while(p->next && p->val == p->next->val)
p = p->next;
p = p->next;
}
}
p = index->next;
index->next = NULL;
while(p != NULL)
{//销毁多余的节点
ListNode *tmp = p;
p = p->next;
delete tmp;
}
head = addHead->next;
delete addHead;
return head;
}
};
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