2025-01-12 双向链表

src/dataANDcalc/java/LinkedList/DoubleLinkedList.java

@@ -0,0 +1,175 @@
+package LinkedList;
+
+import java.util.Scanner;
+
+public class DoubleLinkedList {
+
+    private DoubleLinkedList.DoubleLinkedListNode head = new DoubleLinkedList.DoubleLinkedListNode(0, 0);
+
+    public void add(DoubleLinkedListNode node){
+        DoubleLinkedListNode temp = head;
+        while (true) {
+            if (temp.next == null){
+                break;
+            }
+            temp = temp.next;
+        }
+        temp.next = node;
+        node.prev = temp;
+    }
+
+    public void modify(DoubleLinkedListNode node){
+        DoubleLinkedListNode temp = head;
+        if (head.next == null){
+            System.out.println("链表为空");
+            return;
+        }
+        while (true) {
+            temp = temp.next;
+            if (temp == null){
+                System.out.println("未找到更新的数据");
+                return;
+            }
+            if (temp.nodeId == node.nodeId){
+                temp.data = node.data;
+                System.out.println("数据更新成功");
+                return;
+            }
+        }
+    }
+
+    public void delete(int nodeId){
+        DoubleLinkedListNode temp = head.next;
+        if (temp == null){
+            System.out.println("链表为空");
+            return;
+        }
+        while (true) {
+            if (temp == null){
+                System.out.println("未找到需要删除的节点");
+                return;
+            }
+            if (temp.nodeId == nodeId){
+                if (temp.next == null){
+                    temp.prev.next = null;
+                    return;
+                }
+                temp.next.prev = temp.prev;
+                temp.prev.next = temp.next;
+                return;
+            }
+            temp = temp.next;
+        }
+    }
+
+    private void show(){
+        DoubleLinkedListNode temp = head;
+        if (head.next == null){
+            System.out.println("当前双向链表为空");
+        }
+        while(true){
+            if (temp.next == null){
+                break;
+            }
+            temp = temp.next;
+            System.out.println(temp.print());
+        }
+    }
+
+    public static void main(String[] args) {
+        DoubleLinkedList doubleLinkedList = new DoubleLinkedList();
+        Scanner scan = new Scanner(System.in);
+        while (true) {
+            System.out.println("a添加节点, s查看节点, r按顺序加入, u更新数据, d删除数据 exit退出:");
+            String handle = scan.next();
+            if ("exit".equals(handle)){
+                break;
+            }
+            if ("a".equals(handle)){
+                System.out.println("请输入节点编号:");
+                int no = scan.nextInt();
+                System.out.println("请输入节点数据:");
+                int data = scan.nextInt();
+                DoubleLinkedList.DoubleLinkedListNode node = new DoubleLinkedList.DoubleLinkedListNode(no,data);
+                doubleLinkedList.add(node);
+            }
+            if ("r".equals(handle)){
+                System.out.println("请输入节点编号:");
+                int no = scan.nextInt();
+                System.out.println("请输入节点数据:");
+                int data = scan.nextInt();
+                DoubleLinkedList.DoubleLinkedListNode node = new DoubleLinkedList.DoubleLinkedListNode(no,data);
+            }
+            if ("s".equals(handle)){
+                doubleLinkedList.show();
+            }
+            if ("u".equals(handle)){
+                System.out.println("请输入更新节点编号:");
+                int no = scan.nextInt();
+                System.out.println("请输入更新节点数据:");
+                int data = scan.nextInt();
+                DoubleLinkedList.DoubleLinkedListNode node = new DoubleLinkedList.DoubleLinkedListNode(no,data);
+                doubleLinkedList.modify(node);
+            }
+            if ("d".equals(handle)){
+                System.out.println("请输入删除节点编号:");
+                int no = scan.nextInt();
+                doubleLinkedList.delete(no);
+            }
+        }
+        scan.close();
+    }
+
+    public static class DoubleLinkedListNode{
+        private int nodeId;
+        private int data;
+        private DoubleLinkedListNode next;
+        private DoubleLinkedListNode prev;
+
+        public DoubleLinkedListNode(int nodeId, int data){
+            this.nodeId = nodeId;
+            this.data = data;
+        }
+
+        public int getNodeId() {
+            return nodeId;
+        }
+
+        public void setNodeId(int nodeId) {
+            this.nodeId = nodeId;
+        }
+
+        public int getData() {
+            return data;
+        }
+
+        public void setData(int data) {
+            this.data = data;
+        }
+
+        public DoubleLinkedListNode getNext() {
+            return next;
+        }
+
+        public void setNext(DoubleLinkedListNode next) {
+            this.next = next;
+        }
+
+        public DoubleLinkedListNode getPrev() {
+            return prev;
+        }
+
+        public void setPrev(DoubleLinkedListNode prev) {
+            this.prev = prev;
+        }
+
+        public String print() {
+            return "DoubleLinkedListNode{" +
+                    "nodeId=" + nodeId +
+                    ", data=" + data +
+                    ", next=" + (next == null ? "null" : String.valueOf(next.nodeId)) +
+                    ", prev=" + (prev == null ? "null" : String.valueOf(prev.nodeId)) +
+                    '}';
+        }
+    }
+}

src/dataANDcalc/java/LinkedList/SingleLinkedListExam.java

@@ -0,0 +1,24 @@
+package LinkedList;
+
+public class SingleLinkedListExam {
+
+    // 1.求单向列表中有效节点的个数
+
+    // 2.查找单向链表中倒数第k个节点
+    /*
+        1.统计链表的长度
+        2.根据长度减去k得到实际需要遍历的长度
+        3.根据实际需要遍历的长度获取节点
+    */
+
+    // 3.单向链表的反转
+    /*
+        1.先定义一个新的头节点
+        2.从头到尾遍历原来的链表，每遍历一个节点，就将其放到新的链表的最前端
+        3.将原来的链表头指向新的链表
+    */
+
+    // 4.从尾到头打印单向链表
+
+    // 5.合并两个有序的单向链表，合并之后链表仍然有顺序
+}