203. Remove Linked List Elements¶

#
# @lc app=leetcode id=203 lang=python3
#
# [203] Remove Linked List Elements
#
# https://leetcode.com/problems/remove-linked-list-elements/description/
#
# algorithms
# Easy (46.10%)
# Likes:    7779
# Dislikes: 217
# Total Accepted:    1M
# Total Submissions: 2.1M
# Testcase Example:  '[1,2,6,3,4,5,6]\n6'
#
# Given the head of a linked list and an integer val, remove all the nodes of
# the linked list that has Node.val == val, and return the new head.
#
#
# Example 1:
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# Input: head = [1,2,6,3,4,5,6], val = 6
# Output: [1,2,3,4,5]
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#
# Example 2:
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# Input: head = [], val = 1
# Output: []
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#
# Example 3:
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# Input: head = [7,7,7,7], val = 7
# Output: []
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#
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# Constraints:
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#
# The number of nodes in the list is in the range [0, 10^4].
# 1 <= Node.val <= 50
# 0 <= val <= 50
#
#
#

# @lc code=start
# Definition for singly-linked list.

from typing import Optional


class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next


class Solution:
    def removeElements(self, head: Optional[ListNode], val: int) -> Optional[ListNode]:

        d = ListNode(next=head)

        c = d
        while c.next:

            if c.next.val == val:
                c.next = c.next.next
            else:
                c = c.next

        return d.next

# @lc code=end