反向单链表——代码改进

Question

我正在努力提高我的递归技能（或者可能是第一次获得它们 :)）。为此，我写了一段Java代码来反转一个单链表，如下：

node head, prev; // head is pointing to the start of the linked list

void reverselist(node current) {
    if (current.next != null) {
        reverselist(current.next);
    }
    if (current.next == null) {
        this.head = current;
        prev = current;
    }
    else {
        prev.next = current;
        current.next = null;
        prev = current;
    }
}

这段代码运行良好，但为了学习，我想避免在递归函数内部使用全局变量（node prev）进行操作。那么这个函数是否可以重写来完全避免呢？欢迎任何其他优化:)

Answer 1

一个更好的实现应该如下：

public Node reverse(Node current)
{
 if (current== null || current.next==null) return current;
 Node nextItem = current.next;
 current.next = null;
 Node reverseRest = reverse(nextItem);
 nextItem.next = current;
 return reverseRest;
}

Answer 2

public Linkedlist reverseList (LinkedList list) {

    Node temp = null;
    Node nextNode = list;
    while(list != null) {
        nextNode = list.next;
        list.next = temp;
        temp = list;
        list = nextNode;
    }
    return temp;
}

private class LinkedList {

    int data;
    LinkedList next;
}