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Copy pathRemoveDuplicatesFromSortedListII.cpp
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Copy pathRemoveDuplicatesFromSortedListII.cpp
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49 lines (40 loc) · 1010 Bytes
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/**
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.
[Analysis]
Add a dummy node, the reason is that we may have duplicates starting from head
*/
/**
* 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) {
if (!head || !head->next) return head;
ListNode * pre = new ListNode(0);
pre->next = head;
head = pre;
ListNode* p = head;
while (p->next) {
ListNode* p2 = p->next;
while (p2->next && p2->val == p2->next->val) {
p2 = p2->next;
}
if (p2 != p->next) {
p->next = p2->next;
}
else {
p = p->next;
}
}
return head->next;
}
};