快速切题 sgu 111.Very simple problem 大数 开平方 难度:0 非java:1

111.Very simple problem

time limit per test: 0.5 sec. 
memory limit per test: 4096 KB

You are given natural number X. Find such maximum integer number that it square is not greater than X.

Input

Input file contains number X (1≤X≤101000).

Output

Write answer in output file.

Sample Input

16

Sample Output

4

 开平方的方法懒得写,索性二分,可能的话将来回来写写

实际用时:11min

import java.io.*;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
	public static void main(String []args) throws IOException{
		BigInteger X;
		Scanner scanner=new Scanner(System.in);
		X=scanner.nextBigInteger();
		if(X.compareTo(BigInteger.ONE)==0){
			System.out.println("1");
			return ;
		}
		BigInteger l=BigInteger.ZERO,r=X;
		while(r.compareTo(l.add(BigInteger.ONE))==1){
			BigInteger mid=l.add(r).shiftRight(1);
			int fl=X.compareTo(mid.multiply(mid));
			if(fl==0){
				l=mid;
				break;
			}
			else if(fl==-1){
				r=mid;
			}
			else {
				l=mid;
			}
		}
		System.out.println(l);
	}
}