LeetCode Q83: 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.

	/**
	* 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==NULL)
	return head;
	ListNode* newHead=new ListNode(-1);
	newHead->next=head;
	ListNode* p0=head;
	ListNode* p1=head;
	while(p0->next!=NULL){
	if(p1==NULL){
	p0->next=NULL;
	break;
	}
	if(p0->val==p1->val){
	p1=p1->next;
	}else{
	p0->next=p1;
	p0=p1;
	}
	}
	head=newHead->next;
	delete newHead;
	return head;
	}
	};

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Round 2 solution:

	/**
	* 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==NULL)
	return NULL;
	ListNode* newHead = new ListNode(head->val+1);
	newHead->next=head;
	ListNode* p = newHead;
	ListNode* n = p->next;
	while(n!=NULL){
	if(p->val!=n->val){
	p=p->next;
	n=p->next;
	}else{
	while(n!=NULL&&n->val==p->val){
	n=n->next;
	}
	p->next=n;
	}
	}
	return newHead->next;
	}
	};

view raw Q83.cpp hosted with ❤ by GitHub