链表类常见算法题总结

链表类常见算法题目总结

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1.反转链表

翻转思想：

代码实现：

public class SinglyLinkedList_reverse {

    public static <T> void reverse(MSinglyLinkedList<T> list) {
        Node<T> p = list.head.next, succ = null, front = null;
        while (p != null) {
            succ = p.next;//保存p的后继节点
            p.next = front;//使得p.next指向其前驱front
            front = p;
            p = succ;
        }
        list.head.next = front;
    }

    public static void main(String[] args) {
        String[] values = { "A", "B", "C", "D", "E", "F" };
        MSinglyLinkedList<String> list = new MSinglyLinkedList<String>(values);
        System.out.println("翻转前" + list.toString());
        reverse(list);
        System.out.println("翻转后" + list.toString());

    }
}

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2.给定一个链表，删除链表中倒数第n个节点，返回链表的头节点。

样例
给出链表1->2->3->4->5->null和 n = 2.

删除倒数第二个节点之后，这个链表将变成1->2->3->5->null.

/**
 * @param head: The first node of linked list.
 * @param n: An integer.
 * @return: The head of linked list.
 */
ListNode removeNthFromEnd(ListNode head, int n) {
    if (n <= 0) {
        return null;
    }

    ListNode dummy = new ListNode(0);
    dummy.next = head;

    ListNode preDelete = dummy;
    for (int i = 0; i < n; i++) {
        if (head == null) {
            return null;
        }
        head = head.next;
    }
    while (head != null) {
        head = head.next;
        preDelete = preDelete.next;
    }
    preDelete.next = preDelete.next.next;
    return dummy.next;
}