Squre_root.cpp

#include<iostream>
#define sqr(a) ((a)*(a))
using namespace std;
unsigned long  sqrt(unsigned long a){
	unsigned long l=0,u=a,mid = l+(u-l)/2;	
	while(mid*mid != a){
		if(sqr(mid) < a){
			if(sqr(mid+1)>a){
					return mid;
					}
			l=mid+1;		
		}
		else{
			if(sqr(mid-1)<a){
					return mid;
					}
			u=mid-1;
	
			}

		mid = l+(u-l)/2;
	} 



return mid;

}


int main(){
unsigned long a;
cin>>a;
cout<<"\nSQUARE ROOT of "<<a<<"is "<<sqrt(a)<<"\n";
return 0;
}

finding squre root with log(n) complexity