83.remove-duplicates-from-sorted-list.java

/*
 * @lc app=leetcode id=83 lang=java
 *
 * [83] Remove Duplicates from Sorted List
 *
 * https://leetcode.com/problems/remove-duplicates-from-sorted-list/description/
 *
 * algorithms
 * Easy (43.24%)
 * Likes:    915
 * Dislikes: 86
 * Total Accepted:    363.5K
 * Total Submissions: 838K
 * Testcase Example:  '[1,1,2]'
 *
 * Given a sorted linked list, delete all duplicates such that each element
 * appear only once.
 *
 * Example 1:
 *
 *
 * Input: 1->1->2
 * Output: 1->2
 *
 *
 * Example 2:
 *
 *
 * Input: 1->1->2->3->3
 * Output: 1->2->3
 *
 *
 */
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
  public ListNode deleteDuplicates(ListNode head) {
    if (head == null) {
      return null;
    }
    ListNode prev = head;
    ListNode curr = head.next;
    while (prev != null && curr != null) {
      if (prev.val == curr.val) {
        prev.next = curr.next;
      } else {
        prev = curr;
      }
      curr = curr.next;
    }
    return head;
  }
}