#include<iostream>using namespace std;

int Find(int ar[],int low,int high,int key){ if(low>high)  return -1; int mid = (low+high)/2; if(ar[mid] == key)  return mid; else if(key<ar[mid])  return Find(ar,low,mid-1,key); else  return Find(ar,mid+1,high,key);}void main(){ int ar[]={1,23,45,67,90,123,456,678,900,1000}; int key; cout<<"intput key:"; cin>>key; int n = sizeof(ar) / sizeof(int); int low = 0; int high = n-1; int index=Find(ar,low,high,key); cout<<"index ="<<index<<endl;}