203.RemoveLinkedListElements.cpp

/*
 * @lc app=leetcode id=203 lang=cpp
 *
 * [203] Remove Linked List Elements
 *
 * https://leetcode.com/problems/remove-linked-list-elements/description/
 *
 * algorithms
 * Easy (39.18%)
 * Likes:    2453
 * Dislikes: 119
 * Total Accepted:    436.7K
 * Total Submissions: 1.1M
 * 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
 *
 *
 */

// @lc code=start
/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        ListNode* dummy = new ListNode();
        dummy->next = head;
        ListNode* curr = dummy;
        while (curr && curr->next) {
            while (curr->next->val == val) {
                curr->next = curr->next->next;
            }
            curr = curr->next;
        }
        return dummy->next;
    }
};
// @lc code=end