2. Add Two Numbers

Posted on | In |
  • Source : Link
  • Author : Han
  • Date : 2022-01-10

Problems

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:

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Input: l1 = [2,4,3], l2 = [5,6,4]
Output: [7,0,8]
Explanation: 342 + 465 = 807.

Example 2:

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

Example 3:

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Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
Output: [8,9,9,9,0,0,0,1]

Solution

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class Solution {
    private fun ListNode?.value(): Int = this?.`val` ?: 0

    fun addTwoNumbers(l1: ListNode?, l2: ListNode?, plus: Int = 0): ListNode? = when {
        l1 == null && l2 == null && plus == 0 -> null

        else -> {
            val sum: Int = l1.value() + l2.value() + plus
            ListNode(sum % 10).apply { next = addTwoNumbers(l1?.next, l2?.next, sum / 10) }

        }
    }
}