大数开根号java模板

package lanqiao;

import java.math.BigInteger;
import java.util.Scanner;
public class Main {

static BigInteger cal(BigInteger x){
BigInteger l = BigInteger.ONE ;
BigInteger r = x ;
BigInteger temp = BigInteger.ZERO ;
while(!l.equals(r)){
BigInteger mid = (l.add(r)).divide(BigInteger.valueOf(2)) ;
if(temp.compareTo(BigInteger.ZERO)!=0&&temp.compareTo(mid)==0){
break ;
}else{
temp = mid ;
}
if(temp.compareTo(BigInteger.ZERO)==0){
temp = mid ;
}
if(mid.multiply(mid).compareTo(x)==1){
r=mid ;
}else{
l=mid ;
}
}
if(l.multiply(l).compareTo(x)==1){
l=l.subtract(BigInteger.ONE) ;
}
return l;

}
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in = new Scanner(System.in) ;

while(in.hasNextBigInteger()){
BigInteger n = in.nextBigInteger() ;

BigInteger x = cal(n) ;
System.out.println(x);

}
}

}