c++二分法

如上图，二分法查找，查找的过程是先确定待查找数的范围区间，然后逐步缩小查找范围，直到找到或找不到为止。

c++代码的实现

#include<iostream>
using namespace std;
const int len=10;
int find_array(int a[],int len,int key);
int full_array(int a[],int len);
int main()
{
    int i_array[len];
    full_array(i_array,len);
    cout<<"input the element you want to find"<<endl;
    int key,num;
    cin>>key;
    num=find_array(i_array,len,key);
    if(num!=-1)
    {
        cout<<"successful find"<<i_array[num]<<endl;
    }
    else
    {
        cout<<"not the element"<<endl;
    }

    return 0;
}

int full_array(int *a,int len)
{
    cout<<"please input "<<len<<" element init the array"<<endl;
    int i=0;
    while(i!=len)
    {
        cin>>a[i];
        i++;
    }
    return 0;
}

int find_array(int a[],int len,int key)
{
    int low=0,high=len-1,middle;
    while(low<high)
    {
        middle=(low+high)/2;

        if(key==a[middle])
        {
            return middle ;
        }
        else if(key>a[middle])
        {
            low=middle+1;
        }
        else
        {
            low=middle-1;
        }
        
    }
    return -1;
}

ok。