203.remove-linked-list-elements.java

/*
 * @lc app=leetcode id=203 lang=java
 *
 * [203] Remove Linked List Elements
 *
 * https://leetcode.com/problems/remove-linked-list-elements/description/
 *
 * algorithms
 * Easy (36.31%)
 * Likes:    958
 * Dislikes: 59
 * Total Accepted:    250K
 * Total Submissions: 686K
 * Testcase Example:  '[1,2,6,3,4,5,6]\n6'
 *
 * Remove all elements from a linked list of integers that have value val.
 *
 * Example:
 *
 *
 * Input:  1->2->6->3->4->5->6, val = 6
 * Output: 1->2->3->4->5
 *
 *
 */
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
  public ListNode removeElements(ListNode head, int val) {
    ListNode dummy = new ListNode(0);
    dummy.next = head;
    ListNode prev = dummy;
    ListNode curr = head;
    while (curr != null) {
      if (curr.val == val) {
        prev.next = curr.next;
        curr = curr.next;
      } else {
        prev = curr;
        curr = curr.next;
      }
    }
    return dummy.next;
  }
}