Java实现三种常用的查找算法(顺序查查找，折半查找，二叉排序树查找)

public class Search {

    public class BiTreeNode{

        int m_nValue;

        BiTreeNode m_pLeft;

        BiTreeNode m_pRight;

    }

    //顺序查找，查到则返回该值下标，查不到返回-1.

    public int SequenceSearch(int[] a,int b){

        if(a==null)

            return -1;

        for(int i=0;i<a.length;i++){

            if(a[i]==b)

                return i;

        }

        return -1;

    }

    //折半查找，二分查找,要求查找的数组是有序的。只适合于静态查找。

    public int BinarySearch(int[] a,int b){

        if(a==null)

            return -1;

        int low=0;

        int high=a.length-1;

        while(low<=high){

            int middle=(low+high)/2;

            if(a[middle]==b)

                return middle;

            if(a[middle]<b)

                low=middle+1;

            else

                high=middle-1;

        }

        return -1;

    }

    //折半查找的递归算法

    public int BinarySearch1(int[] a,int b,int low,int high){

        if(a==null||low>high)

            return -1;

        int middle=(low+high)/2;

        if(a[middle]==b)

            return middle;

        if(a[middle]<b)

            return BinarySearch1(a,b,middle+1,high);

        else

            return BinarySearch1(a,b,low,middle-1);

    }

    //二叉排序树，二叉查找树，二查搜索树，是一颗具有如下特点的树，树的左边都比它小，树的右边都比它大。

    public BiTreeNode BinaryBiSearch(BiTreeNode pHead,int b){

        if(pHead==null)

            return null;

        if(pHead.m_nValue==b)

            return pHead;

        if(pHead.m_pLeft!=null)

            return BinaryBiSearch(pHead.m_pLeft,b);

        if(pHead.m_pRight!=null)

            return BinaryBiSearch(pHead.m_pRight,b);

        return null;

    }

    public static void main(String[] args){

        int[] a={1,2,3,5,7,8,10};

        Search search=new Search();

        int i=search.BinarySearch(a,1);

        int k=search.BinarySearch1(a, 3,0,a.length-1);

        int j=search.SequenceSearch(a, 3);

        System.out.println(i+" "+j+" "+k);

    }

}