【LeetCode】【Kotlin】206. Reverse Linked List

題意

將題目給的 ListNode 反轉

題解

將 node 指向的下一個 node 替換成原本的上一個 node

程式碼

/**
 * 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 reverseList(head: ListNode?): ListNode? {
        var head = head
        var front:ListNode? = null
        var next: ListNode? = null
       // var i = 1
        while(head !=  null){
            // println("${i++} ${head.`val`} (next : ${head.next.`val`})")
            //println(i++)
            next = head!!.next
            head!!.next = front
            front = head
            head = next
        }
        return front
    }
}

160ms/36.1 MB (beats 45.63% / 70.37%)