Union of Linked Lists

Now that we've implemented a Linked List, let's start operating on it! Assume you have a Linked List implementation with this definition:

class LinkedList {
    constructor() {
        this.head = null;
        this.tail = null;
    }

    prepend(newVal) {
        const currentHead = this.head;
        const newNode = new Node(newVal);
        newNode.next = currentHead;
        this.head = newNode;

        if (!this.tail) {
            this.tail = newNode;
        }
    }

    append(newVal) {
        const newNode = new Node(newVal);
        if (!this.head) {
            this.head = newNode;
            this.tail = newNode;
        } else {
            this.tail.next = newNode;
            this.tail = newNode;
        }
    }
}

Can you write a method getUnion to find the union of two linked lists? A union of two sets includes everything in both sets.

So given 1 -> 2 -> 3 and 3 -> 4 -> 5, we'd get 1 -> 2 -> 3 -> 4 -> 5.

Constraints

• Length of both the linkedlist <= 1000
• The nodes will always contain integer values between -1000000000 and 1000000000
• Let m, n be the lengths of the two lists
• Expected time complexity : O(n*m)
• Expected space complexity : O(n+m)

```js
function getUnion(list1, list2) {
  // implement a method to get the union
}

class LinkedList {
	constructor() {
		this.head = null;
		this.tail = null;
	}

	prepend(newVal) {
		const currentHead = this.head;
		const newNode = new Node(newVal);
		newNode.next = currentHead;
		this.head = newNode;

		if (!this.tail) {
			this.tail = newNode;
		}
	}

	append(newVal) {
		const newNode = new Node(newVal);
		if (!this.head) {
			this.head = newNode;
			this.tail = newNode;
		} else {
			this.tail.next = newNode;
			this.tail = newNode;
		}
	}

	toString() {
		const toPrint = [];
		let currNode = this.head;

		while (currNode) {
			toPrint.push(currNode.val);
			currNode = currNode.next;
		}

		return toPrint.join(' -> ');
	}
}
```