UVA 10023 Square root

UVA_10023

    今天学了一下手算开平方的算法，其实也没我之前想的那么麻烦，因为懒得敲C++的大数模块，就直接用Java写了。

import java.math.BigInteger;
import java.util.Scanner;

public class Main {
    public static void solve(BigInteger y)
    {
        int i, j;
        BigInteger x = new BigInteger("0");
        String str = "0" + y.toString();
        BigInteger dvs = new BigInteger("0"), rmd = new BigInteger("0");
        i = str.length() % 2;
        for(; i < str.length(); i += 2)
        {
            rmd = rmd.multiply(BigInteger.valueOf(100)).add(new BigInteger(str.substring(i, i + 2)));
            dvs = x.multiply(BigInteger.valueOf(20));
            for(j = 0; j < 10; j ++)
            {
                if(dvs.add(BigInteger.valueOf(j + 1)).multiply(BigInteger.valueOf(j + 1)).compareTo(rmd) == 1)
                {
                    rmd = rmd.add(dvs.add(BigInteger.valueOf(j)).multiply(BigInteger.valueOf(j)).negate());
                    x = x.multiply(BigInteger.valueOf(10)).add(BigInteger.valueOf(j));
                    break;
                }
            }
        }
        System.out.println(x);
    }
    public static void main(String[] args) {
        Scanner cin = new Scanner(System.in);
        int t = 0, tt;
        t = cin.nextInt();
        for(tt = 0; tt < t; tt ++)
        {
            if(tt != 0)
                System.out.println();
            solve(cin.nextBigInteger());
        }
    }
}