sgu-111-111. Very simple problem(java大数)

题意:求有多少个数的平方不大于大数N;1≤N≤10¹⁰⁰⁰

分析:java大数二分

import java.util.Scanner;
import java.math.*;

public class Solution {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner cin=new Scanner(System.in);
        BigInteger bb;
        while(cin.hasNextBigInteger()){
            bb=cin.nextBigInteger();
            BigInteger L=BigInteger.valueOf(1);
            BigInteger R=BigInteger.valueOf(10);
            R=R.pow(500);
            while(L.compareTo(R)<0){
                //System.out.println("L "+L);
                //System.out.println("R "+R);
                BigInteger m=L.add(R.subtract(L).add(BigInteger.valueOf(1)).shiftRight(1));
                //System.out.println("m "+m);
                if(m.pow(2).compareTo(bb)<=0){
                    L=m;
                }
                else{
                    R=m.subtract(BigInteger.valueOf(1));
                }
            }
            System.out.println(L);
        }
    }
}