SGU111 Very simple problem

多少个平方数小于等于X，二分。

PS：java BigInteger。

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

public class Solution {
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);

        BigInteger X = in.nextBigInteger();

        BigInteger L = BigInteger.valueOf(1);
        BigInteger R = BigInteger.valueOf(10).pow(500);

        while (L.compareTo(R) <= 0) {
            BigInteger M = L.add(R).divide(BigInteger.valueOf(2));
            if (M.pow(2).compareTo(X) <= 0) {
                L = M.add(BigInteger.valueOf(1));
            } else {
                R = M.subtract(BigInteger.valueOf(1));
            }
        }

        System.out.println(R);
    }
}