双向链表

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双向链表

双向链表也叫双链表，是链表的一种，它的每个数据结点中都有两个指针，分别指向直接后继和直接前驱。所以，从双向链表中的任意一个结点开始，都可以很方便地访问它的前驱结点和后继结点。

具体操作

属性

    public DoubleLink start;    public DoubleLink last;

1.insertStart

    public void insertStart(int v){        DoubleLink link = new DoubleLink(v);        if(start==null){            start=link;            last=link;        }else {            link.next=start;            start.prev=link;            start=link;        }    }

2.insertLast

    public void insertLast(int v){        DoubleLink link = new DoubleLink(v);        if(last==null){            start=link;            last=link;        }else {            last.next=link;            link.prev=last;            last=link;        }    }

3.insertAfterKey

    public void insertAfterKey(int key,int love){        DoubleLink link = new DoubleLink(love);        DoubleLink t = start;        DoubleLink p = t;        while (t!=null&&t.value!=key){            p = t;            t=t.next;        }        if(t==null){            System.out.println("key is error!");        }else {            if(t.next==null){                t.next=link;                link.prev=t;                last = link;            }else {                t.next.prev=link;                link.next=t.next;                t.next=link;                link.prev=t;            }        }    }

4.deleteStart

    public int deleteStart(){        int v = start.value;        if (start.next==null){            start= null;            last = null;        }else {            start.next.prev=null;            start=start.next;        }        return v;    }

5.deleteLast

    public int deleteLast(){        int v = last.value;        if(last.prev==null){            last=null;            start=null;        }else {            last.prev.next=null;            last=last.prev;        }        return v;    }

6.deleteByKey

    public int deleteByKey(int key){        DoubleLink t = start;        DoubleLink p = t;        while (t!=null&&t.value!=key){            p = t;            t = t.next;        }        if(t==null){            System.out.println("key is error!");            return 0;        }else {            p.next=t.next;            t.next.prev=t.prev;            return t.value;        }    }

7.displayForward

    public void displayForward(){        DoubleLink t = start;        while (t!=null){            System.out.println(t.value);            t=t.next;        }    }

8.displayBackward

    public void displayBackward(){        DoubleLink t = last;        while (t!=null){            System.out.println(t.value);            t=t.prev;        }    }

9.DoubleLink类

public class DoubleLink {    public int value;    public DoubleLink next;    public DoubleLink prev;    public DoubleLink(int value) {        this.value = value;    }}

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