链表的定义

class LN{    int data;    public LN next;    public LN(int data) {        this.data = data;        this.next = null;    }  }

 

链表的新增、按索引删除、按key值删除

public class ListPractice {    static LN head = null;    public static int length;        public static void main(String[] args) {               int[] nums = {1,2,3,4};        for (int i = 0; i < nums.length; i++) {            insertLN(nums[i]);        }        deleteLN(1);        deleteLNIndex(2);        LN q = head;        while(q!=null){            System.out.println(q.data);            q = q.next;        }    }        //插入    public static void insertLN(int num){                LN p = new LN(num);                if(head == null){            head = p;            length++;            return;        }                LN q = head;        while(q.next!=null){            q = q.next;        }        q.next = p;        length++;    }        //按key值删除    public static void deleteLN(int num){        if(head != null){                        LN p = head;            LN q = p.next;                        if(p.data == num){                head = q;            }                        while(q!=null){                if(q.data==num){                    p.next = q.next;                    return;                }                p = q;                q = q.next;            }        }    }            //按索引删除    public static void deleteLNIndex(int index){                LN p = head;        LN q = p.next;                if(index<1||index>length){            return;        }                if(index == 1){            head = head.next;            return;        }                for (int i = 2; i < index; i++) {            p = q;            q = q.next;        }        p.next = q.next;    }}