[leetcode] 2. Add two numbers (Typescript)

문제

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.

 

Example 1:

Input: l1 = [2,4,3], l2 = [5,6,4]

Output: [7,0,8]

Explanation: 342 + 465 = 807.

 

Example 2:

Input: l1 = [0], l2 = [0]

Output: [0]

 

Example 3:

Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]

Output: [8,9,9,9,0,0,0,1]

 

Constraints:

• The number of nodes in each linked list is in the range [1, 100].
• 0 <= Node.val <= 9
• It is guaranteed that the list represents a number that does not have leading zeros.

 

function addTwoNumbers(l1: ListNode | null, l2: ListNode | null): ListNode | null {
    let resultList: ListNode = new ListNode();
    let tempList: ListNode = resultList;
    let roundedNumber: number = 0;
    
    while (true) {
        const l1Val = l1 ? l1.val : 0
        const l2Val = l2 ? l2.val : 0
        tempList.val = l1Val + l2Val + roundedNumber;

        if (tempList.val >= 10) {
            roundedNumber = Math.floor((tempList.val) / 10);
            tempList.val = tempList.val % 10;
        } else {
            roundedNumber = 0;
        }
        
        l1 = l1 ? l1.next : null;
        l2 = l2 ? l2.next : null;

        if (!l1 && !l2) {
            if (roundedNumber >= 1) {
                tempList.next = new ListNode();
                tempList = tempList.next;
                tempList.val = roundedNumber;
            }
            break;
        }

        tempList.next = new ListNode();
        tempList = tempList.next;
    }
    
    return resultList;
};