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LinkedList.js
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LinkedList.js
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class Node {
constructor(val) {
this.value = val;
this.next = null;
}
}
class LinkedList {
// initialize the linked list with one or multiple values
constructor(...nodes) {
this.head = null;
this.tail = null;
this.length = 0;
for (const node of nodes) {
this.push(node);
this.length += 1;
}
}
push(value) {
const newNode = new Node(value);
// if head is null, set head to this
if (!this.head) {
this.head = newNode;
this.tail = newNode;
} else {
this.tail.next = newNode;
this.tail = newNode;
}
this.length += 1;
}
contains(value) {
let current = this.head;
while (current) {
if (current.value === value) {
return true;
}
current = current.next;
}
return false;
}
addToHead(value) {
const newNode = new Node(value);
newNode.next = this.head;
this.head = newNode;
this.length += 1;
}
insert(value, position) {
let depth = 0;
let current = this.head;
let previous;
while (depth < position) {
previous = current;
current = current.next;
depth += 1;
}
const newNode = new Node(value);
newNode.next = current;
if (previous) {
previous.next = newNode;
} else {
this.head = newNode;
}
this.length += 1;
}
removeItem(value) {
// remove first occurrence of value from list
let current = this.head;
let prev = null;
while (current) {
if (current.value === value) {
if (current === this.head) {
this.head = this.head.next;
} else if (current === this.tail) {
this.tail = prev;
prev.next = null;
} else {
prev.next = current.next;
}
}
prev = current;
current = current.next;
}
this.length -= 1;
}
removePosition(position) {
// remove element at specified position in list
let depth = 0;
let current = this.head;
let previous = current;
while (depth < position) {
previous = current;
current = current.next;
depth += 1;
}
while (current) {
if (depth === position) {
// if the node to be removed is the head
// reassign the head
if (this.head && current === this.head) {
this.head = this.head.next;
}
// ditto tail
if (this.tail && current === this.tail) {
this.tail = previous;
this.tail.next = null;
} else {
// node to be removed is in the middle of list
previous.next = current.next;
}
}
this.length -= 1;
return current;
}
}
getLength() {
return this.length;
}
}
module.exports = LinkedList;