BinarySearch的实现

最新推荐文章于 2024-08-11 19:50:52 发布

原创最新推荐文章于 2024-08-11 19:50:52 发布 · 1.3k 阅读

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CC 4.0 BY-SA版权

文章标签：

#integer #recursion #import #string #numbers #input

该博客展示了Java语言实现二分查找算法的代码。包含递归二分查找和稳定二分查找两种方法，通过输入数组大小、元素和目标元素，调用递归二分查找方法查找目标元素，最后输出查找结果、耗时和查找次数。

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package search;

import java.util.*;
import java.io.*;

public class BinarySearch
{
public static int times;
/** recursion binarySearch */
public boolean recursionBinarySearch(Comparable[] data,int min,int max,Comparable target)
{
  times++;
  boolean found = false;
  int midPoint = (min+max)/2;

  if (data[midPoint].compareTo(target) ==0)
  {
   found = true;
  }
  else if (data[midPoint].compareTo(target)>0)
  {
   if (min<= midPoint-1)
       found=binarySearch(data,min,midPoint-1,target);
  }
  else if (midPoint+1 <= max)
  {
   found = binarySearch(data,midPoint+1,max,target);
  }

  return found;
}

public resetTimes()
{
  this.times = 0;
}
public boolean steadyBinarySearch(Comparable[] data,int min, int max,Comparable target)
{
  times++;
  boolean found = false;
  int midPoint = (min+max)/2;

  while(min<max)
  {
   if (data[midPoint].compareTo(target) >0)
    max = midPoint;
   else
    low = midPoint;
  }

  if (data[min].compareTo(target) == 0)
   found = true;
  return found;

}

public static void main(String [] args) throws IOException
{
  String inString ;
  StringTokenizer tokenizer;
  Integer [] elements;
  Comparable target;
  BinarySearch bs = new BinarySearch();

  BufferedReader in = new BufferedReader( new InputStreamReader(System.in));

  //get size
  System.out.println("Please input the size ( size>0 ): ");
  inString = in.readLine();
  elements = new Integer[Integer.parseInt(inString)];

  //get data[]
  System.out.println("Enter the numbers of elements :(gap it with Key_space or Key_tab) ");
  inString = in.readLine();
  tokenizer = new StringTokenizer(inString);
  for (int i =0; i<elements.length && tokenizer.hasMoreTokens();i++)
  {
   elements[i] = Integer.parseInt(tokenizer.nextToken());
  }

  //get target
  System.out.println("Please input target element: ");
  inString = in.readLine();
  target = new Integer(Integer.parseInt(inString));

  long startTime = System.currentTimeMillis();

  boolean found = bs.recursionBinarySearch(elements,0,elements.length-1,target);

  System.out.println("the result: "+found);
  System.out.println("take time = "+(System.currentTimeMillis()-startTime));
  System.out.println("size : "+elements.length+" , cursory times : "+times);
}
}