Remove all elements from a linked list of integers that have value val.
GeeksforGeeks
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Input: 1->2->6->3->4->5->6, val = 6
Output: 1->2->3->4->5
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// Definition for singly-linked list.
public class ListNode {
int val;
ListNode next;
ListNode() {}
ListNode(int val) {
this.val = val;
}
ListNode(int val, ListNode next) {
this.val = val;
this.next = next;
}
}/**
* Time complexity : O(N)
* Space complexity : O(1)
*/
class Solution {
public ListNode removeElements(ListNode head, int val) {
while(head != null && head.val == val) {
head = head.next;
}
if(head == null) return null;
ListNode prev = head;
ListNode curr = head.next;
while(curr != null) {
if(curr.val != val) {
prev.next = curr;
prev = prev.next;
}
curr = curr.next;
}
prev.next = null;
return head;
}
}/**
* Time complexity : O(N)
* Space complexity : O(1)
*/
class Solution {
public ListNode removeElements(ListNode head, int val) {
ListNode newHead = new ListNode(0);
newHead.next = head;
ListNode prev = newHead;
while(prev.next != null) {
if(prev.next.val == val) {
prev.next = prev.next.next;
} else {
prev = prev.next;
}
}
return newHead.next;
}
}