编写代码,移除未排序链表中的重复节点。保留最开始出现的节点。
示例1:
输入:[1, 2, 3, 3, 2, 1]
输出:[1, 2, 3]
示例2:
输入:[1, 1, 1, 1, 2]
输出:[1, 2]
提示:
链表长度在[0, 20000]范围内。
链表元素在[0, 20000]范围内。
进阶: 如果不得使用临时缓冲区,该怎么解决?
来源:力扣(LeetCode) 链接:https://leetcode-cn.com/problems/remove-duplicate-node-lcci 著作权归领扣网络所有。商业转载请联系官方授权,非商业转载请注明出处。
class Solution {
public:
ListNode* removeDuplicateNodes(ListNode* head) {
if(!head || !head->next)
return head;
unordered_set<int> s;
ListNode *prev = head, *cur = head->next;
s.insert(head->val);
while(cur)
{
if(!s.count(cur->val))
{
s.insert(cur->val);
prev = cur;
}
else
prev->next = cur->next;
cur = cur->next;
}
return head;
}
};
class Solution {
public:
ListNode* removeDuplicateNodes(ListNode* head) {
if(!head || !head->next)
return head;
ListNode *prev = head, *cur = head->next, *pc=NULL;
int v;
while(prev)
{
v = prev->val;
pc = prev;
cur = prev->next;
while(cur)
{
if(cur->val != v)
{
pc = cur;
}
else
{
pc->next = cur->next;
}
cur = cur->next;
}
prev = prev->next;
}
return head;
}
};