7递归二分和迭代二分

/*
    递归二分查找_I
    迭代二分查找_R

*/


#include "BinarySearch_I_and_R.h"
#include <iostream>
using namespace std;
int BinarySearch_I(int *a,int nLen,int nTarget);
int BinarySearch_R(int *a,int nTarget,int left,int right);

int main()
{
    int nTest=7;
    const int nLen = 10;
    int m[nLen] = {1,2,3,4,5,6,7,8,9,10};

    int nRet = BinarySearch_I(m,nLen,nTest);
    if (-1 == nRet)
    {
        cout <<"迭代二分:没找到"<<endl;
    }
    else
    {
        cout <<"迭代二分:找到了"<<endl;
    }


    nRet = BinarySearch_R(m,nTest,0,nLen-1);
    if (-1 == nRet)
    {
        cout <<"递归二分:没找到"<<endl;
    }
    else
    {
        cout <<"递归二分:找到了"<<endl;
    }


    

    system("pause");
    return 0;
}


//迭代二分
int BinarySearch_I(int *a,int nLen,int nTarget)
{
    int left = 0;
    int right = nLen-1;
    int mid;

    while(left <= right)
    {
        mid = (left + right) / 2;
        if (nTarget == a[mid])
        {
            return mid;
        }
        else if (nTarget > a[mid])
        {
            left = mid + 1;
        }
        else if (nTarget < a[mid])
        {
            right = mid - 1;
        }

    }

    return -1;
}


//递归二分
int BinarySearch_R(int *a,int nTarget,int left,int right)
{

    if (left <= right)
    {
        int mid = (left + right)/2;
        if (nTarget < a[mid])
        {
            return BinarySearch_R(a,nTarget,left,mid-1);
        }
        else if (nTarget > a[mid])
        {
            return BinarySearch_R(a,nTarget,mid+1,right);
        }
        else
        {

            return mid;
        }
    }


    return -1;
}