C++ :

#include<iostream>
using namespace std;
const int max1=1000000;
int a[max1],n,m;
int  flag;
int search(int ,int, int );
int main()
{  
	cin>>n;
	for (int i=1; i<=n; ++i) cin>>a[i];
	cin>>m;
	flag=search(1,n,m);
	if (flag>0) cout<<"YES"<<endl;
		else  cout<<"NO"<<endl;
	//cout<<flag<<endl;
	return 0;
}
int  search(int l,int r,int m)
{
	int mid=(l+r)/2;
	if (l>r) return -1;
		else if (a[mid]==m) return mid;	
			else if (a[mid]<m) 
				return search(l,mid-1,m);
			else return search(mid+1,r,m);
}

Pascal :

program  binsearch;
var a:array[1..100000] of longint;
    i,n,x,f:longint;
 function binsearch(k:longint):longint;
  var low,hig,mid:longint;
  begin
    low:=1;hig:=n;
    mid:=(low+hig) div 2;
        while (a[mid]<>k) and (low<=hig) do begin
            if a[mid]<k then hig:=mid-1
        else low:=mid+1;
      mid:=(low+hig) div 2;
        end;
    if low>hig then mid:=0;
    binsearch:=mid;
    end;
begin
  readln(n);
  for i:=1 to n do read(a[i]);
  readln(x);
  f:=binsearch(x);
  if f>0 then writeln('YES') else writeln('NO');
end.

Java :

import java.util.*;
public class Main{
	public static void main(String[] args) {
		Scanner input=new Scanner(System.in);
		int n=input.nextInt();
		int []a=new int[n];
		for(int i=0;i<n;i++) {
			a[i]=input.nextInt();
		}
		int tar=input.nextInt();
		
		if(tar==binseach(0,tar,a.length-1, a)) {
			System.out.println("YES");
		}else {
			System.out.println("NO");
		}
		
	}
	public static int binseach(int st,int tar,int end,int []a) {
		if(st>end) {
			return -1;
		}
		int mid=0;
		mid=(st+end)/2;

		if(a[mid]>tar) {
			st=mid+1;
			return binseach(st, tar, end, a);
		}
		if(a[mid]<tar) {
			end=mid-1;
			return binseach(st, tar, end, a);
		}else {
			return a[mid];
		}
		
	}
}