binary.cpp

#include <bits/stdc++.h>
#include <chrono>
using namespace std;
using namespace std::chrono;

int binary_search(int arr[], int first, int last, int key)
{
 if (last >= first) {
 int mid = first + (last - first) / 2;
 if (arr[mid] == key)
 return mid;
 if (arr[mid] > key)
 return binary_search(arr, first, mid - 1, key);
 return binary_search(arr, mid + 1, last, key);
 }
 
 return -1;
}

int main()
{
 int n, mid, last, first=0, key, flag=0, result;
 cout<<"Enter Number of Elements: ";
 cin>>last;
 int arr[last];
 cout<<"Enter elements in Sorted order: ";
 for(int i=0;i<last;i++){
 cin>>arr[i];
 }
 cout<<"Enter Key: ";
 cin>>key;
 auto start = steady_clock::now();
 result = binary_search(arr, first, last, key);
 if (result != -1){
 cout<<"Key Found at index: "<<result<<endl;
 }
 else{
 cout<<"Key not Found"<<endl;
 }
 auto stop = steady_clock::now();
 auto duration = duration_cast<nanoseconds>(stop - start);
 cout << "\nTime taken by function: "<< duration.count() << " nanoseconds" << endl;
}