【数据结构算法（二）】链表总结

🌈键盘敲烂，年薪30万🌈

普通单向链表

双向链表

带哨兵的链表

环形链表

⭐双向带头带环链表的实现⭐

⭐链表基础OJ⭐

普通单向链表

结点结构：只有val 和 next指针

初始时：head = null;

双向链表

指针：prev指针 val next指针

初始时：head = null;

带哨兵的链表

初始时：new 一个新节点sentinel val不重要，next = null

环形链表

尾节点的next指向头结点

初始时：头结点的next指向自己

⭐双向带头带环链表的实现⭐

准备工作

public class TheBestLinkedList implements Iterable<Integer>{private Node sentinel = new Node(null, 666, null);public TheBestLinkedList() {sentinel.prev = sentinel;sentinel.next = sentinel;}private static class Node{Node prev;int val;Node next;public Node(Node prev, int val, Node next) {this.prev = prev;this.val = val;this.next = next;}}@Overridepublic Iterator<Integer> iterator() {return null;}
}

addFirst

    public void addFirst(int val){Node newNode = new Node(sentinel, val, null);Node first = sentinel.next;newNode.next = first;first.prev = newNode;sentinel.next = newNode;}

addLast

    public void addLast(int val){Node newNode = new Node(null, val, sentinel);Node last = sentinel.prev;last.next = newNode;newNode.prev = last;sentinel.prev = newNode;}

removedLast

    public Node removedLast(){if(isEmpty()){return null;}Node last = sentinel.prev;Node removedPrev = last.prev;sentinel.prev = removedPrev;removedPrev.next = sentinel;return last;}

removedFirst

    public Node removedFirst(){if(isEmpty()){return null;}Node first = sentinel.next;// 只有一个节点 removedNext = sentinelNode removedNext = first.next;sentinel.next = removedNext;removedNext.prev = sentinel;return first;}

isEmpty

    public boolean isEmpty(){return sentinel.prev == sentinel;}

迭代器遍历

    @Overridepublic Iterator<Integer> iterator() {return new Iterator<Integer>() {Node p = sentinel.next;@Overridepublic boolean hasNext() {return p != sentinel;}@Overridepublic Integer next() {int ans =  p.val;p = p.next;return ans;}};}