leeCode -Add Two Numbers(LinkedList)

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.

 

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풀이

const addTwoNumbers = function (l1, l2) {
    let pointer1 = l1;
    let pointer2 = l2;

    let head = new ListNode();
    let headPointer = head;
    let carry = 0;

    while (pointer1 || pointer2) {

        let val1 = pointer1 ? pointer1.val : 0;
        let val2 = pointer2 ? pointer2.val : 0;

        let nodeSum = carry + val1 + val2
        if (nodeSum > 9) {
            carry = 1;
        } else {
            carry = 0;
        }

        headPointer.next = new ListNode(nodeSum % 10);
        headPointer = headPointer.next;

        pointer1 = pointer1 ? pointer1.next : null;
        pointer2 = pointer2 ? pointer2.next : null;
    }
    if (carry) {
        headPointer.next = new ListNode(carry);
    }
    return head.next;
};