[导入]Java实现折半查找(二分查找)的递归和非递归算法

[导入]Java实现折半查找(二分查找)的递归和非递归算法

Java二分查找实现,欢迎大家提出交流意见.

/**
*名称:BinarySearch
*功能:实现了折半查找(二分查找)的递归和非递归算法.
*说明:
*     1、要求所查找的数组已有序,并且其中元素已实现Comparable<T>接口,如Integer、String等.
*    2、非递归查找使用search();,递归查找使用searchRecursively();
*
*本程序仅供编程学习参考
*
*@author:   Winty
*@date:     2008-8-11
*@email:    [email][email protected][/email]
*/

class BinarySearch<T extends Comparable<T>> {
     private T[]  data; //要排序的数据

     public BinarySearch(T[] data){
         this.data = data;
    }

     public int search(T key){
         int low;
         int high;
         int mid;

         if(data == null)
             return -1;

        low = 0;
        high = data.length - 1;

         while(low <= high){
            mid = (low + high) / 2;
            System.out.println( "mid " + mid + " mid value:" + data[mid]);///
            
             if(key.compareTo(data[mid]) < 0){
                high = mid - 1;
            } else if(key.compareTo(data[mid]) > 0){
                low = mid + 1;
            } else if(key.compareTo(data[mid]) == 0){
                 return mid;
            }
        }

         return -1;
    }

     private int doSearchRecursively( int low , int high , T key){
         int mid;
         int result;

         if(low <= high){
            mid = (low + high) / 2;
            result = key.compareTo(data[mid]);
            System.out.println( "mid " + mid + " mid value:" + data[mid]);///
            
             if(result < 0){
                 return doSearchRecursively(low , mid - 1 , key);
            } else if(result > 0){
                 return doSearchRecursively(mid + 1 , high , key);
            } else if(result == 0){
                 return mid;
            }
        }
        
         return -1;
    }

     public int searchRecursively(T key){
         if(data == null) return -1;

         return doSearchRecursively(0 , data.length - 1 , key);
    }

     public static void main(String[] args){
        Integer[] data = {1 ,4 ,5 ,8 ,15 ,33 ,48 ,77 ,96};
        BinarySearch<Integer> binSearch = new BinarySearch<Integer>(data);
         //System.out.println("Key index:" + binSearch.search(33) );

        System.out.println( "Key index:" + binSearch.searchRecursively(3) );

         //String [] dataStr = {"A" ,"C" ,"F" ,"J" ,"L" ,"N" ,"T"};
         //BinarySearch<String> binSearch = new BinarySearch<String>(dataStr);
         //System.out.println("Key index:" + binSearch.search("A") );
    }
}

文章来源: http://wintys.blog.51cto.com/425414/94051