203. Remove Linked List Elements
Remove Linked List Elements
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 <= 500 <= val <= 50
Let`s Code IT!
/**
* Definition for singly-linked list.
* function ListNode(val, next) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {ListNode} head
* @param {number} val
* @return {ListNode}
*/
var removeElements = function(head, val) {
if (head === null) {
return head;
}
let currentNode = head;
let previousNode;
while(currentNode != null){
if(currentNode.val == val){
if(currentNode == head){
currentNode = head.next;
head.next = null;
head = currentNode;
continue;
}else{
previousNode.next = currentNode.next;
currentNode.next = null;
currentNode = previousNode.next;
continue;
}
}
previousNode = currentNode;
currentNode = currentNode.next;
}
return head;
};Complexity
Time Complexity
We traverse the Linked list from left to right only once, hence the time complexity will be O(n).
Space Complexity
We are using two extra linked list space for currentNode and previousNode hence the space complexity will be O(n)
Resources:
Conclusion
That’s all folks! In this post, we solved LeetCode problem #203. Remove Linked List Elements
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You can find the complete source code on my GitHub repository. If you like what you learn. feel free to fork 🔪 and star ⭐ it.
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Happy coding!
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