/*

Author: King, wangjingui@outlook.com

Date: Dec 12, 2014

Problem: Remove Duplicates from Sorted List

Difficulty: Easy

Source: https://oj.leetcode.com/problems/remove-duplicates-from-sorted-list/

Notes:

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.

Solution: 1. Delete duplicates directly.

2. Copy value first (like Remove Duplicates from Array) and then delete the remaining elements.

*/

/**

* 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_1(ListNode head) {

if(head == null || head.next == null) return head;

ListNode pre = head, cur = head.next;

while(cur != null) {

if(pre.val == cur.val) {

pre.next = cur.next;

} else {

pre = pre.next;

}

cur = cur.next;

}

return head;

}

public ListNode deleteDuplicates(ListNode head) {

if(head == null || head.next == null) return head;

ListNode pre = head, cur = head.next;

while(cur != null) {

if (pre.val != cur.val) {

pre.next.val = cur.val;

pre = pre.next;

}

cur = cur.next;

}

pre.next = null;

return head;

}

}