Kotlin Leetcode - 2. Add Two Numbers

題目連接

class Solution {
    fun addTwoNumbers(l1: ListNode?, l2: ListNode?): ListNode? {
    }
}

解題思路

本題練習的是針對 linked list 的操作

在 Kotlin 解題需要注意的是 val 是關鍵字

所以需要 以 `` 標記

Kotlin 參考解答

點擊展開解答

class Solution {
    fun addTwoNumbers(l1: ListNode?, l2: ListNode?): ListNode? {
        val head = ListNode(0)
        var cursor = head
        var node1 = l1
        var node2 = l2
        var carry = 0

        while (node1 != null || node2 != null) {
            val sum = (node1?.`val` ?: 0) + (node2?.`val` ?: 0) + carry
            cursor.next = ListNode(sum % 10)
            cursor = cursor.next

            carry = if (sum > 9) 1 else 0
            if (node1 != null) node1 = node1?.next
            if (node2 != null) node2 = node2?.next
        }

        if (carry > 0) {
            cursor.next = ListNode(carry)
            cursor = cursor.next
        }

        return head?.next
    }
}

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