[LeetCode79]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.

Analysis:

The idea is to use two pointer to scan, compare and remove the duplicates from the start to end.

if p1.val == p2.val, p2 = p2.next

else p1.next = p2, p1 = p1.next, p2 = p2.next

c++

ListNode *deleteDuplicates(ListNode *head) {    if(head==NULL||head->next==NULL) return head;    ListNode *p1 = head;    ListNode *p2 = head->next;    while(p2!=NULL){        if(p1->val == p2->val){            p2 = p2->next;        }        else{            p1->next = p2;            p2 = p2->next;            p1 = p1->next;        }    }    p1->next = p2;    return head;}

Java

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.       ListNode n1=head;       while(n1 != null && n1.next !=null){       if(n1.val == n1.next.val){       n1.next = n1.next.next;       }       else       n1 = n1.next;       }       return head;    }