203. Remove Linked List Elements

Problem Statement

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:

Input: head = [1,2,6,3,4,5,6], val = 6
Output: [1,2,3,4,5]

Example 2:

Input: head = [], val = 1
Output: []

Example 3:

Input: head = [7,7,7,7], val = 7
Output: []

Constraints:

The number of nodes in the list is in the range [0, 10⁴].
1 <= Node.val <= 50
0 <= val <= 50

Solution:

package main

// Definition for singly-linked list.
type ListNode struct {
	Val  int
	Next *ListNode
}

// Iterative
func removeElements(head *ListNode, val int) *ListNode {
	if head == nil {
		return nil
	}
	for head != nil && head.Val == val {
		head = head.Next
	}
	if head == nil {
		return nil
	}
	for p := head; p.Next != nil; {
		if p.Next.Val == val {
			p.Next = p.Next.Next
		} else {
			p = p.Next
		}
	}

	return head
}

// Recursive
func removeElementsRecursive(head *ListNode, val int) *ListNode {
	if head == nil {
		return nil
	}
	head.Next = removeElementsRecursive(head.Next, val)
	if head.Val == val {
		return head.Next
	}
	return head
}

203. Remove Linked List Elements #

Problem Statement #

Solution: #

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203. Remove Linked List Elements

Problem Statement

Solution:

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