AddTwoNumbers.kt

/**
 * Example:
 * var li = ListNode(5)
 * var v = li.`val`
 * Definition for singly-linked list.
 * class ListNode(var `val`: Int) {
 *     var next: ListNode? = null
 * }
 */
class Solution {
    fun addTwoNumbers(l1: ListNode?, l2: ListNode?): ListNode? {
        val head = ListNode(0)
        var i = l1
        var j = l2
        var curr = head
        var cnt = 0

        while (j != null || i != null) {
            val x = i?.`val` ?: 0
            val y = j?.`val` ?: 0

            val temp = x+y+cnt
            cnt = temp/10
            curr.next = ListNode(temp%10)
            curr = curr.next
            if (i != null) i = i?.next
            if (j != null) j = j?.next
        }
        if (cnt > 0) {
            curr.next = ListNode(cnt)
        }
        return head.next
    }
}