null

DROP DATABASE IF EXISTS Hospital; CREATE DATABASE Hospital; USE Hospital; CREATE TABLE Doctor ( id INT PRIMARY KEY AUTO_INCREMENT, NAME VARCHAR(20) NOT NULL, age INT NOT NULL, major VARCHAR(20) NOT NULL ); INSERT INTO Doctor VALUES (NULL,'张三',30,' 骨科'); INSERT INTO Doctor VALUES (NULL,'李四',35,'心血管'); INSERT INTO Doctor VALUES (NULL,'王五',40,'妇产科'); SELECT * FROM Doctor; 来源： https://www.cnblogs.com/adeepbluesky/p/12047813.html

简述 将两个有序的链表合并，并返回 输入： 1 -> 2 -> 4 , 1 -> 3 -> 4 输出： 1 -> 1 -> 2 -> 3 -> 4 -> 4 代码 /** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */ class Solution { public : ListNode * mergeTwoLists ( ListNode * l1 , ListNode * l2 ) { ListNode * head = NULL , * cur = NULL ; int val ; while ( l1 || l2 ) { if ( l1 != NULL && l2 != NULL ) { if ( l1 -> val < l2 -> val ) { val = l1 -> val ; l1 = l1 -> next ; } else { val = l2 -> val ; l2 = l2 -> next ; } } else if ( l1 != NULL ) { val = l1 -> val ; l1 = l1 -> next ; } else if

java根据文件头判断文件类型 package com.mytest; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.util.HashMap; import java.util.Iterator; import java.util.Map; public class VerifyFileType { public final static Map<String, String> FILE_TYPE_MAP = new HashMap<String, String>(); private static FileInputStream is; static { getAllFileType(); // 初始化文件类型信息 } /** * 常用文件格式 */ private static void getAllFileType() { FILE_TYPE_MAP.put("ffd8ffe000104a464946", "jpg"); // JPEG (jpg) FILE_TYPE_MAP.put("89504e470d0a1a0a0000", "png"); // PNG (png) FILE_TYPE_MAP

package task1 ; /** * 功能：单链表增删操作 * Created by liumao 2019/8/4 **/ public class SingleLinkedList { // 定义链表结点 class Node { // 数据域 int data ; // 指针域 Node next ; public Node ( int data , Node next ) { this . data = data ; this . next = next ; } } public static void main ( String [ ] args ) { SingleLinkedList sLinkedList = new SingleLinkedList ( ) ; sLinkedList . insertvalue ( 1 ) ; sLinkedList . insertvalue ( 2 ) ; sLinkedList . insertvalue ( 3 ) ; sLinkedList . insertvalue ( 4 ) ; System . out . println ( "插入后：" ) ; sLinkedList . print ( ) ; // System.out.println("按索引查找：" + sLinkedList

package task1 ; /** * 功能：双向链表实现增删操作 * Created by liumao 2019/8/4 **/ public class DoubleLinkList < T > { private Link < T > prior ; private Link < T > next ; class Link < T > { public T val ; public Link < T > next ; public Link < T > pre ; public Link ( T val ) { this . val = val ; } public void displayCurrentNode ( ) { System . out . println ( val + " " ) ; } } //初始化首尾指针 public DoubleLinkList ( ) { prior = null ; next = null ; } public boolean isEmpty ( ) { return prior == null ; } //从尾部依次增加，下标往后移 public void addList ( T value ) { Link < T > newLink = new Link ( value ) ; if ( isEmpty ( ) )