82. 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.

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10/01 YC version:

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        
        if(head == null || head.next == null)
            return head;
            
        ListNode cur = head;
        while(cur.next!=null){
            if(cur.val == cur.next.val)
                cur.next = cur.next.next;
            else
                cur = cur.next;
        }
        
        return head;
        
    }
}

 

 

old version

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        
        if(head == null) return null;
         
        ListNode prev = head
        ListNode cur = head.next;        
    
        while(cur != null) {
               
            if(cur.val == prev.val) {
                prev.next = cur.next;
                cur = cur.next;
            }else{
                prev = cur;
                cur = cur.next;
            }
        
        }
    
        return head;

    }
}