单向链表

反转单向链表

    static Node reverseByRecursion(Node head) {
        if (head == null || head.next == null) {
            return head;
        }
        Node newHead = reverseByRecursion(head.next);
        head.next.next = head;
        head.next = null;
        return newHead;
    }
   static Node reverseByLoop(Node head) {
        if (head == null || head.next == null) {
            return head;
        }
        Node preNode = null;
        Node nextNode;
        while (head != null) {
            nextNode = head.next;
            head.next = preNode;
            preNode = head;
            head = nextNode;
        }
        return preNode;
    }

单链表查找倒数第k个节点

    static Node findKnode(Node head, int k) {
        if (k < 1 || k > length(head)) {
            return null;
        }
        Node p1 = head;
        Node p2 = head;
        for (int i = 0; i < k - 1; i++) {
            p2 = p2.next;
        }
        while (p2.next != null) {
            p2 = p2.next;
            p1 = p1.next;
        }
        return p1;
    }

单链表递归倒序打印

    public static void printListReversely(Node head) {
        if (head != null) {
            printListReversely(head.next);
            if (head != null) {
                System.out.println(head.data);
            }
        }
    }

单链表排序

    public static void sort(Node head) {
        Node currentNode;
        Node nextNode;
        for (currentNode = head; currentNode.next != null; currentNode = currentNode.next) {
            for (nextNode = head; nextNode.next != null; nextNode = nextNode.next) {
                if (nextNode.data > nextNode.next.data) {
                    int temp = nextNode.data;
                    nextNode.data = nextNode.next.data;
                    nextNode.next.data = temp;
                }
            }
        }
    }

单链表删除重复节点

 public static void removeDuplicate(Node head) {
        HashSet set = new HashSet();
        Node temp = head;
        Node pre = null;
        while (temp != null) {
            if (set.contains(temp.data)) {
                pre.next = temp.next;
            } else {
                set.add(temp.data);
                pre = temp;
            }
            temp = temp.next;
        }
    }