折半查找

阿里笔试的时候考了，回来写了下。

#include <iostream>

using namespace std;



int BinarySearch(int array[], int lenght, int key)
{
    
    
    int low = 0; 
    int high = lenght - 1;
    int mid;
    while (low <= high){
        mid = (low + high)/2;
        if(array[mid] == key){
            
            printf("%d
",array[mid]);
            return array[mid];
            }
        else if(array[mid] > key)
            high = mid - 1;
        else 
            low = mid + 1;
    }
     
    return -1;
}


void test0()
{
    int array[10] = {0,1,2,3,4,5,6,7,8,9};
    if(BinarySearch(array, 10, 5) == 5)
    {
        printf("-------------------------passed
");
    }
    else
    {
        printf("-------------------------failed
");
    }    
}

void test1()
{
    int array[10] = {0,1,2,3,4,5,6,7,8,9};
    if(BinarySearch(array, 10, 15) == -1)
    {
        printf("-------------------------passed
");
    }
    else
    {
        printf("-------------------------failed
");
    }    
}
void test2()
{
    int array[1] = {0};
    if(BinarySearch(array, 1, 15) == -1)
    {
        printf("-------------------------passed
");
    }
    else
    {
        printf("-------------------------failed
");
    }    
}
void test3()
{
    int array[1] = {0};
    if(BinarySearch(array, 1, 0) == 0)
    {
        printf("-------------------------passed
");
    }
    else
    {
        printf("-------------------------failed
");
    }    
}
void test4()
{
    int array[10] = {0,1,2,3,4};
    if(BinarySearch(array, 5, 4) == 4)
    {
        printf("-------------------------passed
");
    }
    else
    {
        printf("-------------------------failed
");
    }    
}
int main()
{
    test0();
    test1();
    test2();
    test3();
    test4();
}