实验七--查找算法

来源：互联网发布：最新软件开发平台编辑：程序博客网时间：2024/06/03 14:21

一、实验目的：

1. 熟练掌握常用的顺序查找法，折半查找法等查找算法。

2. 深入理解各种查找算法的结构特点及各算法之间的区别。

二、实验内容：

1．常用的一些查找算法。

2．各种查找算法的结构特点及各算法之间的区别。

三、实验要求:

阅读以下四个类：

RecordNode.java

SeqList_Sort.java

Search_Manager.java

Sort_Test.java

将SeqList_Sort.java中的三个查找方法补充完整。

源程序见附件

RecordNode.java

----------------------RecordNode.java ---------------------

package Search;

import java.util.Scanner;

public class RecordNode

{

publicint key ; // 关键字,用整型可以直接用关系运算符比较大小

publicString element; // 记录的其它部分，用字符串，方便输出

Scannersin = new Scanner(System.in);

publicRecordNode()

{

System.out.println("请输入关键字：");

this.key=sin.nextInt();

System.out.println("请输入元素值：");

this.element=sin.next();

}

publicRecordNode(int key)

{

this.key=key;

}

publicRecordNode(int key , String element)

{

this.element= element;

this.key=key;

}

publicString toString()

{

returnthis.key+" "+this.element+" ";

}

----------------------RecordNode.java ---------------------

-------------------- SeqList_Search.java-------------------

/**

*构造用于排序的线性表，

*元素位置从下标1开始

*分别设置各种不同的查找算法

*查找成功，返回位序，查找失败，返回 0

**/

package Search;

import Search.RecordNode;

import java.util.Scanner;

import java.util.Random;

public class SeqList_Search

{

publicRecordNode [ ] r;

publicint curlen;

publicSeqList_Search(int maxSize) //构造方法，用参数做为线性表的初始空间大小

{

this.curlen=0;

this.r= new RecordNode[maxSize];

}

publicSeqList_Search() //构造方法，以默认100做为初始空间大小

{

this(100);

}

publicvoid create(int n) // 输入生成线性表，参数为输入元素个数

{

Scanner sin =new Scanner(System.in);

System.out.println("\t输入"+n+"个线性表的元素：");

for(inti=1;i<=n;i++)

{

try{

RecordNodenewdata=new RecordNode ();

this.insert(i,newdata);

}

catch(Exceptione)

{

System.out.println("\t插入位置不合适，无法创建");

}

publicvoid create( )// 随机数生成10个元素

{

System.out.println("\t生成"+10+"个线性表的元素");

for(inti=1;i<=10;i++)

{

try{

Randomrd = new Random();

RecordNodenewdata = new RecordNode(rd.nextInt(100),"A"+i);

this.insert(i,newdata);

}

catch(Exceptione)

{

System.out.println("\t插入位置不合适，无法创建");

}

publicvoid clear()//清空

{

this.curlen=0;

}

publicboolean isEmpty() //判断是否为空

{

if( this.curlen ==0 )

return true;

else

return false;

}

publicint length() //求长度

{

returnthis.curlen;

}

publicRecordNode get(int i) throws Exception //求指定位置元素

{

if( i < this.curlen)

return this.r[i];

else

{

thrownew Exception("elem no."+i+" not exist!");

}

publicvoid insert(int i,RecordNode x)throws Exception //在指定的位置上插入数据元素

{

if(this.curlen == this.r.length)

{

// throw new Exception("overflow!");

RecordNode newlist[]=newRecordNode[2*this.curlen];

for(int j=this.curlen;j>0;j--)

{

newlist[j]=this.r[j];

}

this.r=newlist;

}

if(i<1|| i>this.curlen+1)

thrownew Exception("position error!");

for(intj =this.curlen ; j >=i ; j-- )

{

this.r[j+1] =this.r[j] ;

}

this.r[i]=x;

this.curlen++;

}

publicvoid remove(int i) //删除指定位置上的元素

{

for(int j = i+1 ; j<= this.curlen ; j++)

{

this.r[j-1]=this.r[j];

}

this.curlen--;

}

publicint indexOf(RecordNode x)

{

int i;

for( i=this.curlen; i>0 ; i--)

{

if(this.r[i].equals(x))

break;

}

return i;

}//查找指定元素的位置

publicvoid display()

{

System.out.println("\n\t线性表的元素是");

for(int i = 1; i <= curlen ;i++)

{

System.out.println("\t"+this.r[i]);

}

System.out.println();

}//输出线性表的所有元素值

//---------------------Search---------------------------

//---------------------seqSearch---------------------------

public int seqSearch(int Key)

{

//顺序查找

int i = 1,n = length();

while(i<n&&r[i].key!=Key)

{

i++;

}

if(i<n)

{

return i;

}

else

{

return 0;

}

//---------------------seqSearchWithGuard---------------------------

publicint seqSearchWithGuard(int Key)

{

r[0]= new RecordNode(Key);

//带岗哨的顺序查找

inti = length();

r[0].key= Key;

while(r[i].key!=Key)

{

i--;

}

if(i>0)

{

returni;

}

else

{

return0;

}

//---------------------binarySearch---------------------------

publicint binarySearch(int Key)

{

//折半查找

if(length()>0)

{

int low = 0,high =length()-1;

while(low<=high)

{

int mid = (low+high)/2;

if(r[mid].key==Key)

{

return mid;

}

elseif(r[mid].key!=Key)

{

high = mid - 1;

}

else

{

low = mid+1;

}

return 0;

}

//---------------------seqSearch------------------------

}

---------------------SeqList_Search.java-------------------

---------------------SeqList_Manager.java------------------

package Search;

import Search.RecordNode;

import Search.SeqList_Search;

import java.util.Scanner;

public class Search_Manager

{

staticScanner sin = new Scanner(System.in);

SeqList_Search test ;

publicSearch_Manager()

{

test= new SeqList_Search ();

}

private void seqSearch() throws Exception

{

test.create();

test.display();

int Search_Key ;

int Search_result = 0 ;

System.out.println("输入待查找的关键字值：");

Search_Key= sin.nextInt();

Search_result =test.seqSearch(Search_Key);

if(Search_result != 0)

{

System.out.println("查找成功，查找结果是：");

System.out.println(test.get(Search_result).toString());

}

test.clear();

}

private void seqSearchWithGuard() throws Exception

{

test.create();

test.display();

int Search_Key ;

int Search_result = 0 ;

System.out.println("输入等查找的关键字值：");

Search_Key= sin.nextInt();

Search_result=test.seqSearchWithGuard(Search_Key);

if(Search_result != 0)

{

System.out.println("查找成功，查找结果是：");

System.out.println(test.get(Search_result).toString());

}

test.clear();

}

private void binarySearch() throws Exception

{

System.out.println("请按关键字有序输入创建查找表：");

test.create(10);

test.display();

int Search_Key ;

int Search_result = 0 ;

System.out.println("输入要查找的关键字的值：");

Search_Key = sin.nextInt();

Search_result=test.binarySearch(Search_Key);

if(Search_result != 0)

{

System.out.println("查找成功，查找结果是：");

System.out.println(test.get(Search_result).toString());

}

test.clear();

}

voidrun () throws Exception

{

System.out.println(" ---------Menu--------");

System.out.println(" 1 seqSearch");

System.out.println(" 2 seqSearchWithGuard ");

System.out.println(" 3 binarySearch");

System.out.println(" 0 Quit ");

System.out.println(" ---------end----------");

System.out.print(" 请选择查找算法：");

intchoice = sin.nextInt();

if(choice == 0 )

System.exit(0);

switch(choice)

{

case1: seqSearch();

break;

case2: seqSearchWithGuard();

break;

case3: binarySearch();

break;

default:System.out.println("error,end");break;

}

System.out.println("_______请继续选择_________");

} while(true);

}

---------------------SeqList_Manager.java------------------

---------------------SeqList_Test.java---------------------

package Search;

import Search.Search_Manager;

import java.util.Scanner;

public class Search_Test

{

publicstatic void main(String [] args) throws Exception

{

newSearch_Manager().run();

}

---------------------SeqList_Test.java---------------------

远行结果如下：

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