[해커랭크] Sherlock and Squares

[해커랭크] Sherlock and Squares

 

https://www.hackerrank.com/challenges/sherlock-and-squares/problem?isFullScreen=true

Sherlock and Squares | HackerRank

 

Watson likes to challenge Sherlock's math ability. He will provide a starting and ending value that describe a range of integers, inclusive of the endpoints. Sherlock must determine the number of square integers within that range.

Note: A square integer is an integer which is the square of an integer, e.g. .

Example

There are three square integers in the range:  and . Return .

Function Description

Complete the squares function in the editor below. It should return an integer representing the number of square integers in the inclusive range from  to .

squares has the following parameter(s):

• int a: the lower range boundary
• int b: the upper range boundary

Returns

• int: the number of square integers in the range

Input Format

The first line contains , the number of test cases.
Each of the next  lines contains two space-separated integers,  and , the starting and ending integers in the ranges.

Constraints

Sample Input

2
3 9
17 24

Sample Output

2
0

Explanation

Test Case #00: In range ,  and  are the two square integers.
Test Case #01: In range , there are no square integers.

 

 

 

 

 

 

 

풀이

이분탐색일줄 알았으나, 단순 제곱근 계산 문제였다.

a와 b에 대한 제곱근을 구하고 소수점처리 해주면 된다.

import java.io.*;

import java.math.*;

import java.security.*;

import java.text.*;

import java.util.*;

import java.util.concurrent.*;

import java.util.function.*;

import java.util.regex.*;

import java.util.stream.*;

import static java.util.stream.Collectors.joining;

import static java.util.stream.Collectors.toList;

class Result {

    /*

     * Complete the 'squares' function below.

     *

     * The function is expected to return an INTEGER.

     * The function accepts following parameters:

     *  1. INTEGER a

     *  2. INTEGER b

     */

     

    public static boolean isSquareNum(double n) {

        int sqrtResult = (int) Math.sqrt(n);

        boolean isSquareNum = (sqrtResult*sqrtResult == n) ? true : false;

        return isSquareNum;

    }

    public static int squares(int a, int b) {

    // Write your code here

       

        // 1 ~ 1,000,000,000

        // 1 ~ 31,622

       

        // System.out.println(Math.pow(7, 2)); // 49

        // System.out.println(Math.pow(8, 2)); // 64

        // System.out.println(Math.sqrt(50));  // 7.xxx

       

        // a=100, b=1000

        double sqrtA = Math.sqrt(a);    // 10.0

        double sqrtB = Math.sqrt(b);    // 31.xxx

       

        int sqrtAint = isSquareNum(a) ? (int) sqrtA : (int) sqrtA + 1;     // 10

        int sqrtBint = (int) sqrtB;     // 31

       

        int count = sqrtBint - sqrtAint + 1;

       

        // System.out.println(sqrtA + " " + sqrtB + " " + sqrtAint + " " + sqrtBint);

       

        return count;

    }

}

public class Solution {

    public static void main(String[] args) throws IOException {

        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        int q = Integer.parseInt(bufferedReader.readLine().trim());

        IntStream.range(0, q).forEach(qItr -> {

            try {

                String[] firstMultipleInput = bufferedReader.readLine().replaceAll("\\s+$", "").split(" ");

                int a = Integer.parseInt(firstMultipleInput[0]);

                int b = Integer.parseInt(firstMultipleInput[1]);

                int result = Result.squares(a, b);

                bufferedWriter.write(String.valueOf(result));

                bufferedWriter.newLine();

            } catch (IOException ex) {

                throw new RuntimeException(ex);

            }

        });

        bufferedReader.close();

        bufferedWriter.close();

    }

}