Leetcode - Reversed Linked List

最新推荐文章于 2024-01-12 14:53:46 发布

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本文介绍了两种逆转链表的方法：一种是逐个节点逆转，另一种是依次将后面节点提前。详细步骤和代码实现帮助理解链表操作。

Reverse a singly linked list.

// method 1: 逐个节点逆转
    public ListNode reverseList1(ListNode head) {
        if (head == null || head.next == null)
            return head;
        
        ListNode prev = head;
        ListNode curr = prev.next;
        prev.next = null; // miss this line will lead to daed loop when print the result list
        ListNode next;
        while (curr != null) {
            next = curr.next;
            curr.next = prev;
            prev = curr;
            curr = next;
        }
        return prev;
    }
    // method 2: 依次将后面节点提前
    public ListNode reverseList(ListNode head) {
        if (head == null)
            return head;
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        ListNode p = head;
        ListNode q = null;
        while (p.next != null) {
            q = p.next;
            p.next = q.next;
            q.next = dummy.next;
            dummy.next = q;
        }
        return dummy.next;
    }