203. Remove Linked List Elements

• Difficulty: Easy

• Topics: Linked List

• Similar Questions:

  • Remove Element

  • Delete Node in a Linked List

Problem:

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

Solutions:

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        ListNode* dummy = new ListNode(0);
        ListNode* tail = dummy;

        ListNode* next = nullptr;

        while (head) {
            next = head->next;
            if (head->val != val) {
                tail->next = head;
                tail = tail->next;
                tail->next = nullptr;
            }
            head = next;
        }

        return dummy->next;
    }
};