JAVA实现单链表的增删查改方法。
单链表
单链表是一种链式存取的数据结构，用一组地址任意的存储单元存放线性表中的数据元素。链表中的数据是以结点来表示的，每个结点的构成：元素(数据元素的映象) + 指针(指示后继元素存储位置)，元素就是存储数据的存储单元，指针就是连接每个结点的地址数据。
代码实现
class Node {
public int data;
public Node next;
public Node(int data) {
this.data = data;
this.next = null;
}
}
public class SingleLinkedList {
public Node head;
//构造方法
public SingleLinkedList() {
this.head = null;
}
//头插法
public void addFirst(int data) {
Node node = new Node(data);
if (this.head == null) {
this.head = node;
return;
}
node.next = this.head;
this.head = node;
}
//尾插法
public void addLast(int data) {
Node node = new Node(data);
if (this.head == null) {
this.head = node;
return;
}
Node cur = this.head;
while(cur.next != null) {
cur = cur.next;
}
cur.next = node;
}
//任意位置插入,第一个数据节点为0号下标
public void addIndex(int index, int data) {
int end = size() -1;
if(index == 0) {
addFirst(data);
}
if(index == end) {
addLast(data);
}
if (index > 0 && index < end) {
Node prev = this.head;
Node cur = prev.next;
int count = 0;
while (cur != null) {
count++;
if (count == index ) {
Node node = new Node(data);
prev.next = node;
node.next = cur;
}
cur = cur.next;
prev = prev.next;
}
}
}
//查找是否包含关键字key是否在单链表当中
public boolean contains(int key) {
Node cur = this.head;
while(cur.next != null) {
if(cur.data == key) {
return true;
}
cur = cur.next;
}
return false;
}
//删除第一次出现关键字为key的节点
public void remove(int key) {
Node prve = this.head;
Node cur = prve.next;
if(this.head.data == key) {
this.head = prve.next;
}
else {
while (cur != null) {
if (cur.data == key) {
prve.next = cur.next;
return;
}
cur = cur.next;
prve = prve.next;
}
}
}
//删除所有值为key的节点
public void removeAllKey(int key) {
Node prev = this.head;
if(this.head.data == key) {
this.head = this.head.next;
}
Node cur = prev.next;
while(cur != null) {
if (cur.data == key) {
prev.next = cur.next;
cur = cur.next;
} else {
prev = cur;
cur = cur.next;
}
if(this.head.data == key) {
this.head = this.head.next;
}
}
}
//得到单链表的长度
public int size() {
int count = 0;
Node cur = this.head;
while(cur != null) {
cur = cur.next;
count++;
}
return count;
}
// 打印
public void display() {
Node cur = this.head;
while (cur != null) {
System.out.println(cur.data);
cur = cur.next;
}
}
//全部删除链表
public void clear() {
//this.head = null;
Node cur = this.head.next;
while(cur != null) {
this.head.next = cur.next;
cur = cur.next;
}
this.head = null;
}
// 反转链表
public void reverseList() {
Node prev = null;
Node cur = this.head;
while(cur != null) {
Node curNext = cur.next;
if(curNext == null) {
this.head = cur;
}
cur.next = prev;
prev = cur;
cur = curNext;
}
}
//在一个排序的链表中，存在重复的结点，请删除该链表中重复的结点
public void deleteDuplication() {
Node cur = this.head;
Node node = new Node(-1);
Node tmp = node;
while (cur != null) {
if(cur.next != null && cur.data == cur.next.data) {
while(cur.next != null && cur.data == cur.next.data) {
cur = cur.next;
}
cur = cur.next;
}
else {
tmp.next = cur;
tmp = cur;
cur = cur.next;
}
}
tmp.next = null;
this.head = node.next;
}
//返回链表的中间结点。
public void middleNode() {
Node slow = this.head;
Node fast = this.head;
while(fast != null && fast.next != null ) {
slow = slow.next;
fast = fast.next.next;
}
slow.next = null;
this.head = slow;
}
//输入一个链表，输出该链表中倒数第k个结点。
public void FindKthToTail(int k) {
Node slow = this.head;
Node fast = this.head;
if(k < 1 || k > size()) {
return;
}
for(int i = 0;i < k - 1;i++) {
fast = fast.next;
}
while(fast.next != null) {
fast = fast.next;
slow = slow.next;
}
slow.next = null;
this.head = slow;
}
public void cycle() {
Node cur = this.head;
while(cur.next != null) {
cur = cur.next;
}
cur.next = this.head.next.next;
}
//给定一个链表，返回链表开始入环的第一个节点。 如果链表无环，则返回 null
public Node detectCycle() {
Node fast = this.head;
Node slow = this.head;
while(fast != null && fast.next != null) {
fast = fast.next.next;
slow = slow.next;
if(fast == slow) {
break;
}
}
if(fast == null && fast.next == null) {
return null;
}
slow = this.head;
while(fast != null && fast.next != null) {
fast = fast.next;
slow = slow.next;
if (fast == slow) {
break;
}
}
this.head = slow;
slow.next = null;
return slow;
}
//是否是链表环
public boolean hasCycle() {
Node fast = this.head;
Node slow = this.head;
while(fast != null && fast.next != null) {
fast = fast.next.next;
slow = slow.next;
if(fast == slow) {
return true;
}
}
return false;
}
//输入两个链表，找出它们的第一个公共结点
public Node getIntersectionNode(Node headA, Node headB) {
if(headA == null || headB == null) {
return null;
}
int lenA = 0;
int lenB = 0;
Node pL = headA;//代表长的单链表
Node pS = headB;//代表短的单链表
while (pL != null) {
lenA++;
pL = pL.next;
}
while (pS != null) {
lenB++;
pS = pS.next;
}
//如果不指回来 那么pl和ps是空
pL = headA;
pS = headB;
int len = lenA-lenB;
if (len < 0) {
pL = headB;
pS = headA;
len = lenB-lenA;
}
//可以保证：
// 1、pL指向了长的单链表 pS指向了短的单链表
//2、len的值 是一个正数
while (len > 0) {
pL = pL.next;
len--;
}
//pL 走了差值len步
while (pL != pS) {
pS = pS.next;
pL = pL.next;
}
//pL == pS
if(pL==pS && pL != null){
return pL;
}
return null;
}
//创建一个交叉链表；
public void crossLinkedlist(Node head , Node head2) {
while ( head.next != null) {
head = head.next;
}
head.next = head2.next.next;
}
//链表的回文结构
public boolean chkPalindrome() {
Node slow = this.head;
Node fast = this.head;
while(fast != null&&fast.next != null) {
fast = fast.next.next;
slow = slow.next;
}
fast = this.head;
Node cur = slow;
Node prev = slow;
while(cur != null) {
Node curNext = cur.next;
cur.next = prev;
prev = cur;
cur = curNext;
}
cur = prev;
while(fast != slow ) {
if(fast.data != cur.data) {
return false;
}
fast = fast.next;
cur = cur.next;
}
return true;
}
//合并链表
public void mergeList(Node head1,Node head2) {
Node cur = head1;
while(cur.next!= null) {
cur = cur.next;
}
cur.next = head2;
}
}