Week 10 homework

Week 10 homework (make-up class test)

1. Summary of knowledge points

1. Singly linked list

• Create a singly linked list
• Insertion of data in linked listlist.add("**");
• Sorting of data in linked listCollections.sort();
• Deletion of data in linked listlsit.remove("");

2. Sort

• tree set concept
• tree mapTreeMap<K,V>**适合用于数据的排序**
• Sort by keywordTreeMap<StudentKey,Student> treemap= new TreeMap<StudentKey,Student>();

2. Supplementary content and screenshots

1. Singly linked list

• Create linked list
  

• create node
  

• Insert your own student number and sort
  

• Delete your student ID and print
  

• overall code

  import java.util.*;
  public class MyList {
  public static void main(String [] args) {
      List<String> mylist=new LinkedList<String>();
  //选用合适的构造方法，用你学号前后各两名同学的学号创建四个结点
      mylist.add("20165224");
      mylist.add("20165225");
      mylist.add("20165227");
      mylist.add("20165228");
  //把上面四个节点连成一个没有头结点的单链表
      System.out.println("打印初始链表");
  //遍历单链表，打印每个结点的
      Iterator<String> iter=mylist.iterator();
      while (iter.hasNext()){
          String num=iter.next();
          System.out.println(num);
      }
  //把你自己插入到合适的位置（学号升序）
      mylist.add("20165226");
      Collections.sort(mylist);
  //遍历单链表，打印每个结点的
      System.out.println("插入我的学号在排序之后，链表中的数据：");
      iter =mylist.iterator();
      while(iter.hasNext()){
          String num=iter.next();
          System.out.println(num);
      }
  //从链表中删除自己
      mylist.remove("20165226");
      System.out.println("删除我的学号之后打印链表：");
  //遍历单链表，打印每个结点的
      iter=mylist.iterator();
      while(iter.hasNext()){
          String num=iter.next();
          System.out.println(num);
      }
  }
  }

• operation result
  

2. Sort

• Create Studentobject of class
  

• Use TreeMap sorting method
  

• 总成绩Sort by keyword
  

• 学号Sort by keyword
  

• operation result
  

3. Make up the programming topic of Chapter 15 of the textbook

1. Use the stack structure to output several items of an, where an=2an-1 +2an-2, a1=3, a2=8

import java.util.*; 
public class E {
public static void main(String args[]) {
Stack<Integer> stack=new Stack<Integer();
       stack.push(new Integer(3));
        stack.push(new Integer(8));
       int k=1;
       while(k<=10) {
         for(int i=1;i<=2;i++) {
           Integer F1=stack.pop();
           int f1=F1.intValue();
           Integer F2=stack.pop();
           int f2=F2.intValue(); 
          Integer temp=new Integer(2*f1+2*f2);
           System.out.println(""+temp.toString());
            stack.push(temp);
           stack.push(F2);
           k++;
         }
       }
     }
 }

2. Write a program to store the students' English transcripts in the linked list into a tree set, so that they can be automatically sorted by grades and output the sorting results

import java.util.*; 
class Student implements Comparable {
    int english=0; 
String name; 
   Student(int english,String name) {
       this.name=name;
       this.english=english;
    } 
   public int compareTo(Object b) {
       Student st=(Student)b;
       return (this.english-st.english);
    }
 } 
public class E { 
  public static void main(String args[]) { 
     List<Student> list=new LinkedList<Student>();
      int score []={65,76,45,99,77,88,100,79}; 
     String name[]={"张三","李四","旺季","加戈","为哈","周和","赵李","将集"};
       for(int i=0;i<score.length;i++){ 
             list.add(new Student(score[i],name[i]));
      } 
     Iterator<Student> iter=list.iterator(); 
     TreeSet<Student> mytree=new TreeSet<Student>();
      while(iter.hasNext()){
          Student stu=iter.next();
          mytree.add(stu);
      } 
     Iterator<Student> te=mytree.iterator();
      while(te.hasNext()) {
         Student stu=te.next(); 
        System.out.println(""+stu.name+" "+stu.english);
      }
   }
 }

3. There are 10 U disks with two important attributes: price and capacity. Write an application that uses TreeMap

 import java.util.*; 
class UDiscKey implements Comparable {
     double key=0;
     UDiscKey(double d) {
      key=d;
    } 
   public int compareTo(Object b) {
      UDiscKey disc=(UDiscKey)b; 
     if((this.key-disc.key)==0)
         return -1;
      else 
        return (int)((this.key-disc.key)*1000);
   }
 } 
class UDisc{
      int amount;
     double price; 
    UDisc(int m,double e) {
        amount=m;
         price=e;
    }
 } 
public class E { 
   public static void main(String args[ ]) { 
      TreeMap<UDiscKey,UDisc>  treemap= new TreeMap<UDiscKey,UDisc>();
       int amount[]={1,2,4,8,16};
       double price[]={867,266,390,556};
       UDisc UDisc[]=new UDisc[4];
       for(int k=0;k<UDisc.length;k++) { 
         UDisc[k]=new UDisc(amount[k],price[k]);
       } 
      UDiscKey key[]=new UDiscKey[4];
        for(int k=0;k<key.length;k++) { 
         key[k]=new UDiscKey(UDisc[k].amount);        } 
      for(int k=0;k<UDisc.length;k++) { 
         treemap.put(key[k],UDisc[k]);                 } 
      int number=treemap.size(); 
      Collection<UDisc> collection=treemap.values();
       Iterator<UDisc> iter=collection.iterator();
       while(iter.hasNext()) {
          UDisc disc=iter.next(); 
         System.out.println(""+disc.amount+"G "+disc.price+"元");       } 
      treemap.clear(); 
      for(int k=0;k<key.length;k++) { 
 key[k]=new UDiscKey(UDisc[k].price);       } 
      for(int k=0;k<UDisc.length;k++) {
          treemap.put(key[k],UDisc[k]);       } 
      number=treemap.size();
       collection=treemap.values();
       iter=collection.iterator();
       while(iter.hasNext()) {
          UDisc disc=iter.next(); 
         System.out.println(""+disc.amount+"G "+disc.price+"元");
       }
     }
 }