二分查找法(C++ 模板实现)

/*算法总结  二分查找法:  二分查找法的前提是数据已经排序,时间平均复杂度为 O(lgn)  欢迎转载,转载请注明作者 [e-mail]*/#include <iostream>#include <stdio.h>using namespace std;#include <vector>using std::vector;#include <algorithm>/** * @brief binarySearch 二分查找 * @param array 排序后的数组 * @param value 待查找的参数 * @return true on success ,false on failure */template<typename T>bool binarySearch(vector<T> &array,T value){    int low = 0;    int high = array.size () -1;    while ( low <= high )    {        int middle = ( low + high ) /2;        if ( array[middle] == value )        {            return true;        }        else if ( array[middle] > value )        {            high = middle - 1;        }        else if ( array[middle] < value )        {            low = middle + 1;        }    }    return false;}void unitTest(){    vector<int> vec;    for ( int i = 0 ; i < 100 ; i += 2 )    {        vec.push_back (i);    }    bool result = binarySearch<int>(vec,29);    cout << "search result for [29]  " << result<<endl;    result = binarySearch<int>(vec,16);    cout << "search result for [16]  " << result<<endl;    vector<string> strVect;    strVect.push_back ("world");    strVect.push_back ("hello");    strVect.push_back ("b");    strVect.push_back ("a");    strVect.push_back ("i love cpp");    sort(strVect.begin (),strVect.end ());    result = binarySearch<string>(strVect,"notfind");    cout << "search result for [notfind]  " << result<<endl;    result = binarySearch<string>(strVect,"world");    cout << "search result for [world]  " << result<<endl;}int main(int argc, char *argv[]){    unitTest ();    return 0;}
下面是递归的实现
#include <iostream>
using namespace std;
template<typename T>
int
bSearch( T array[], T value,int start,int end )
{
    if ( start > end )
    {
        return -1;
    }
    int middle = (start + end)/2;
    if ( array[middle] == value )
    {
        return middle;
    }
    else if ( array[middle] > value )
    {
        return bSearch(array,value,start,middle-1);
    }
    else if ( array[middle] < value )
    {
        return bSearch(array,value,middle+1,end);
    }
}
int main(int argc, char *argv[])
{
    int array[] = {1,2,3,4,5,6,7,8,10,12,32,45};
    int index = bSearch(array,7,0,sizeof(array)/sizeof(array[0])-1);
    cout << index << " " << array[index]<<endl;
    index = bSearch(array,12,0,sizeof(array)/sizeof(array[0])-1);
    cout << index << " " << array[index]<<endl;
    return 0;
}