掌握折半查找算法的思想及程序实现。

代码：

#include <bits/stdc++.h>
using namespace std;
typedef struct BSearch{
    int elem[20];
public:
    void ini(){
        for(int i=0;i<20;i++) elem[i]=rand()%91;
        sort(elem,elem+20);
    }
    int Find(int x){
        int l=0,r=19,mid;
        while(l+1<=r){
            mid=(l+r)/2;
            if(elem[mid]<x){
                l=mid+1;
            }else
                r=mid;
        }
        return l;
    }
    void show(){
        for(int i=0;i<20;i++)
            cout<<elem[i]<<' ';
        cout<<endl;
    }
}BSearch;
int main()
{
    srand((unsigned long long)time(0));
    BSearch a;
    a.ini();
    a.show();
    int x,t;
    while(cin>>x){
        cout<<a.Find(x)<<endl;
    }
}