Immutable fractions

29/07/2015 by Valeriya Rud

Задание

Создайте класс для выполнения основных операций с дробями. В данном варианте дроби не должны изменяться после создания, а методы, реализующие арифметические операции должны быть статическими. Реализуйте метод для автоматического получения строкового представления дроби при печати. Протестируйте своё решение в методе main().
Желательно реализовать метод сокращения дробей через алгоритм Евклида для поиска наибольшего общего делителя (НОД, GCD). Вполне уместной было бы реализовать в этом классе интерфейс Comparable и продемонстрировать работу метода java.util.Arrays.sort().

Решение

class Fraction {
	final int numerator, denominator;
	static String delimiter = "/";
	
	private int gcd(int a, int b){
		while(b != 0){
			int c = a % b;
			a = b;
			b = c;
		}
		return a;
	}

	public static Fraction addition(Fraction x, Fraction y) {
		Fraction z = new Fraction(x.numerator * y.denominator + y.numerator * x.denominator, x.denominator * y.denominator);
		return z;
	}
	
	public static Fraction substraction(Fraction x, Fraction y){
		Fraction z = new Fraction(x.numerator * y.denominator - y.numerator * x.denominator, x.denominator * y.denominator);
		return z;
	}
	
	public static Fraction multiplication(Fraction x, Fraction y){
		Fraction z = new Fraction(x.numerator * y.numerator, x.denominator * y.denominator);
		return z;
	}
	
	public static Fraction division (Fraction x, Fraction y){
		Fraction z = new Fraction(x.numerator * y.denominator, x.denominator * y.numerator);
		return z;
	}
	public String toString(){
		return numerator  + delimiter + denominator; 
	}
	
	public Fraction(){// name ofthe constructor starts from upper case
		numerator = 1;
		denominator = 2;
	}		
		
	public Fraction(int d){
		numerator = 1;
		denominator = d;
	}

	public Fraction(int n, int d){
		int devider = gcd(n, d);
		numerator  = n / devider;
		denominator = d / devider;
	}
	
	public Fraction(Fraction x){
		numerator = x.numerator;
		denominator = x.denominator;
	}

	public static void main (String[] args) {	
		System.out.println(new Fraction(2147483647, 2147483645));
		Fraction x = new Fraction(5);
		System.out.println(x);
		Fraction y = x;
		System.out.println(y);
		Fraction z = new Fraction(x); //copy of x
		System.out.println(z);
		System.out.println(Fraction.addition(x, z));
		System.out.println(Fraction.substraction(z, x));
		System.out.println(Fraction.multiplication(x, z));
		System.out.println(Fraction.division(x, z));
	}
}
}

class Fraction {

final int numerator, denominator;

static String delimiter = "/";

private int gcd(int a, int b){

while(b != 0){

int c = a % b;

a = b;

b = c;

}

return a;

}

public static Fraction addition(Fraction x, Fraction y) {

Fraction z = new Fraction(x.numerator * y.denominator + y.numerator * x.denominator, x.denominator * y.denominator);

return z;

}

public static Fraction substraction(Fraction x, Fraction y){

Fraction z = new Fraction(x.numerator * y.denominator - y.numerator * x.denominator, x.denominator * y.denominator);

return z;

}

public static Fraction multiplication(Fraction x, Fraction y){

Fraction z = new Fraction(x.numerator * y.numerator, x.denominator * y.denominator);

return z;

}

public static Fraction division (Fraction x, Fraction y){

Fraction z = new Fraction(x.numerator * y.denominator, x.denominator * y.numerator);

return z;

}

public String toString(){

return numerator + delimiter + denominator;

}

public Fraction(){// name ofthe constructor starts from upper case

numerator = 1;

denominator = 2;

}

public Fraction(int d){

numerator = 1;

denominator = d;

}

public Fraction(int n, int d){

int devider = gcd(n, d);

numerator = n / devider;

denominator = d / devider;

}

public Fraction(Fraction x){

numerator = x.numerator;

denominator = x.denominator;

}

public static void main (String[] args) {

System.out.println(new Fraction(2147483647, 2147483645));

Fraction x = new Fraction(5);

System.out.println(x);

Fraction y = x;

System.out.println(y);

Fraction z = new Fraction(x); //copy of x

System.out.println(z);

System.out.println(Fraction.addition(x, z));

System.out.println(Fraction.substraction(z, x));

System.out.println(Fraction.multiplication(x, z));

System.out.println(Fraction.division(x, z));

}

Wallpainter

28/07/2015 by Valeriya Rud

Task

One construction company wants to minimize paint expenses. For this reason has to be made a program which can calculate an amount of a paint for the each order. Usually the owner know the longness L , wideness W , and highness H of the each room. Also one can of pain is good enough to paint 16 m², and the size of windows and doors are not important in this calculation

Input:

In the first line should be orders` amount. In the each next line — L, W, H and the wideness, longness, and highness are not more than 1000 .

Output:

For the each order will be shown one one number, what is required amount of the paint cans

Tests

Input	Output
2
8 8 2	4
1 1 3	1
10 6 2	4
11 6 2	5

Solution

Task «Repair» can be solved by using Data Strim processing.

import java.util.*;
import java.io.*;

class Main{
	public static void main (String[] args) throws java.lang.Exception{
		Scanner s = new Scanner(System.in);
		double order = s.nextDouble();
		for(int i = 0; i < order; i++){
			double l = s.nextDouble();
			double w = s.nextDouble();
			double h = s.nextDouble();
			int quantity =(int)Math.ceil(h * (l + w) / 8);
			System.out.println(quantity);
		}
	}
}

import java.util.*;

import java.io.*;

class Main{

public static void main (String[] args) throws java.lang.Exception{

Scanner s = new Scanner(System.in);

double order = s.nextDouble();

for(int i = 0; i < order; i++){

double l = s.nextDouble();

double w = s.nextDouble();

double h = s.nextDouble();

int quantity =(int)Math.ceil(h * (l + w) / 8);

System.out.println(quantity);

}

Between two values

20/07/2015 by Valeriya Rud

Task

Were given three real numbers x, y, z. Check whether the inequality [latex]x < y < z[/latex] is correct. If it is correct, show as an result the word «true». If it is not correct, show as an result the word «false».

Tests

Input	Output
8 9 25	true
9 25 8	false
8 25 9	false
9 8 25	false
25 8 9	false
25 9 8	false

Solution

With «if» statement:

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

class Main{
	public static void main (String[] args) throws java.lang.Exception {
		Scanner s = new Scanner(System.in);	
		int x = s.nextInt();
		int y = s.nextInt();
		int z = s.nextInt();
                
		if(x < y && y < z) {
			System.out.println("true");
		}
		else {
			System.out.println("false");
		}
		s.close();
	}
}

import java.util.*;

class Main{

public static void main (String[] args) throws java.lang.Exception {

Scanner s = new Scanner(System.in);

int x = s.nextInt();

int y = s.nextInt();

int z = s.nextInt();

if(x < y && y < z) {

System.out.println("true");

}

else {

System.out.println("false");

}

s.close();

}

Code refactoring

import java.util.*;
import java.util.*;
 
class Main{
	public static void main (String[] args) throws java.lang.Exception {
		Scanner s = new Scanner(System.in);	
		int x = s.nextInt();
		int y = s.nextInt();
		int z = s.nextInt();
	
		System.out.println(x < y && y < z? true : false);		
		s.close();
	}
}

import java.util.*;

class Main{

public static void main (String[] args) throws java.lang.Exception {

Scanner s = new Scanner(System.in);

int x = s.nextInt();

int y = s.nextInt();

int z = s.nextInt();

System.out.println(x < y && y < z? true : false);

s.close();

}

Find the maximum of three numbers

20/07/2015 by Valeriya Rud

Task. Were given three real numbers [latex]x[/latex], [latex]y[/latex], [latex]z[/latex]. Find [latex]\max (x, y, z)[/latex].

Tests

Input	Output
4 3 8	8
0 179 45	179

Solution

With if-statement

import java.util.*;
class Main{
public static void main (String[] args) throws java.lang.Exception {
Scanner s = new Scanner(System.in);
while(s.hasNextInt()){
int x = s.nextInt();
int y = s.nextInt();
int z = s.nextInt();

if(x > y && x > z){
System.out.println("Maximum number is: " + x);
}

else if(y > z &&  y > x){
System.out.println("Maximum number is: " + y);
}

else{
System.out.println("Maximum number is: " + z);
}

//by using Math method from Java library 
int max =Math.max(Math.max(x,y),z);
System.out.println("Max number is: " + max);
}

s.close();
}
}

import java.util.*;

class Main{

public static void main (String[] args) throws java.lang.Exception {

Scanner s = new Scanner(System.in);

while(s.hasNextInt()){

int x = s.nextInt();

int y = s.nextInt();

int z = s.nextInt();

if(x > y && x > z){

System.out.println("Maximum number is: " + x);

}

else if(y > z && y > x){

System.out.println("Maximum number is: " + y);

}

else{

System.out.println("Maximum number is: " + z);

}

//by using Math method from Java library

int max =Math.max(Math.max(x,y),z);

System.out.println("Max number is: " + max);

}

s.close();

}

Code refactoring

<pre class="lang:java decode:true ">import java.util.*;

class Main{
     public static void main (String[] args) throws java.lang.Exception {
          Scanner s = new Scanner(System.in);
          int x = s.nextInt();
          int y = s.nextInt();
          int z = s.nextInt();

          //solution with Java Library method
          System.out.println(Math.max(Math.max(x,y),z));

          //solution with code refactoring without IF statement
          System.out.println(x > y && x > z ? x : y > z && z > x ? y : z); 
 
         s.close();
     }
}

<pre class="lang:java decode:true ">import java.util.*;

class Main{

public static void main (String[] args) throws java.lang.Exception {

Scanner s = new Scanner(System.in);

int x = s.nextInt();

int y = s.nextInt();

int z = s.nextInt();

//solution with Java Library method

System.out.println(Math.max(Math.max(x,y),z));

//solution with code refactoring without IF statement

System.out.println(x > y && x > z ? x : y > z && z > x ? y : z);

s.close();

}

Find the minimum of two numbers

17/07/2015 by Valeriya Rud

Task. Were given two real numbers [latex]x[/latex] and [latex]y[/latex]. Find [latex]\min (x, y)[/latex].

Tests

Input	Output
758 843	Maximum number is: 843
459 238	Maximum number is: 459

Solution

With if-statement

import java.util.*;

class Main {
    public static void main (String[] args) throws java.lang.Exception {
        Scanner s = new Scanner(System.in);
        int x = s.nextInt();
        int y = s.nextInt();
       
        if (x &lt; y) System.out.println("Minimum number is: " + x);
        else System.out.println("Minimum number is: " + y);
        s.close();
    }
}

import java.util.*;

class Main {

public static void main (String[] args) throws java.lang.Exception {

Scanner s = new Scanner(System.in);

int x = s.nextInt();

int y = s.nextInt();

if (x < y) System.out.println("Minimum number is: " + x);

else System.out.println("Minimum number is: " + y);

s.close();

}

Code refactoring

Without if-statement

import java.util.*;

class Main {
    public static void main (String[] args) throws java.lang.Exception {
        Scanner s = new Scanner(System.in);
        int x = s.nextInt();
        int y = s.nextInt();
        s.close();
        System.out.println("Minimum number is: " + (x &lt; y? x : y));
    }
}

import java.util.*;

class Main {

public static void main (String[] args) throws java.lang.Exception {

Scanner s = new Scanner(System.in);

int x = s.nextInt();

int y = s.nextInt();

s.close();

System.out.println("Minimum number is: " + (x < y? x : y));

}

Matrix Transpose

17/07/2015 by Valeriya Rud

Транспонирование матрицы

Задача. Введите из стандартного потока матрицу и выведите её в транспонированном виде.

Three flowers

17/07/2015 by Valeriya Rud

Задача взята с сайта e-olymp.com.

В рождественский вечер на окошке стояло три цветочка, слева на право: герань, крокус и фиалка. Каждое утро Маша вытирала окошко и меняла местами стоящий справа цветок с центральным цветком. А Таня каждый вечер поливала цветочки и меняла местами левый и центральный цветок. Требуется определить порядок цветов ночью по прошествии k дней.

Входные данные

Первая строка содержит количество тестов m (1 ≤ m ≤ 12). В каждой из следующих m строк находится количество дней k (1 ≤ k ≤ 1000).

Выходные данные

Вывести m строк, содержащих по три латинских буквы: «G», «C» и «V» (заглавные буквы без пробелов), описывающие порядок цветов на окошке по истечении k дней (слева направо). Обозначения: G – герань, C – крокус, V – фиалка.

Тесты

Input	Output
2
1	VGC
5	CVG

Решение

Find the minimum of three numbers

15/07/2015 by Valeriya Rud

Task. Were given three real numbers [latex]x[/latex], [latex]y[/latex], [latex]z[/latex]. Find [latex]\min (x, y, z)[/latex].

Tests

Input	Output
7 8 9	7
8771 1346574 1131	1131

Solution

With if-statement

import java.util.*;

class Main{
     public static void main (String[] args) throws java.lang.Exception {
          Scanner s = new Scanner(System.in);
          int x = s.nextInt();
          int y = s.nextInt();
          int z = s.nextInt();

          //solution with IF statement
          if(x < y && x < z) {
               System.out.println(x);
          } else if(y < z && y < x) {
               System.out.println(y);
          } else {
               System.out.println(z);
          }

          s.close();
     }
}

import java.util.*;

class Main{

public static void main (String[] args) throws java.lang.Exception {

Scanner s = new Scanner(System.in);

int x = s.nextInt();

int y = s.nextInt();

int z = s.nextInt();

//solution with IF statement

if(x < y && x < z) {

System.out.println(x);

} else if(y < z && y < x) {

System.out.println(y);

} else {

System.out.println(z);

}

s.close();

}

Code refactoring

import java.util.*;

class Main{
     public static void main (String[] args) throws java.lang.Exception {
          Scanner s = new Scanner(System.in);
          int x = s.nextInt();
          int y = s.nextInt();
          int z = s.nextInt();

          //solution with Java Library method
          System.out.println(Math.min(Math.min(x,y),z));

          //solution with code refactoring without IF statement
          System.out.println(x < y && x < z ? x : y < z && z < x ? y : z); 
 
          s.close();
     }
}

import java.util.*;

class Main{

public static void main (String[] args) throws java.lang.Exception {

Scanner s = new Scanner(System.in);

int x = s.nextInt();

int y = s.nextInt();

int z = s.nextInt();

//solution with Java Library method

System.out.println(Math.min(Math.min(x,y),z));

//solution with code refactoring without IF statement

System.out.println(x < y && x < z ? x : y < z && z < x ? y : z);

s.close();

}

Find the maximum of two numbers

15/07/2015 by Valeriya Rud

Task. Were given two real numbers [latex]x[/latex] and [latex]y[/latex]. Find [latex]\max (x, y)[/latex].

Tests

Input	Output
758 843	Maximum number is: 843
459 238	Maximum number is: 459

Solution

import java.util.Scanner;

class Main {
	public static void main (String[] args) throws java.lang.Exception {
		Scanner s = new Scanner(System.in);
		int x = s.nextInt();
		int y = s.nextInt();
		System.out.println("Maximum number is: " + (x > y? x : y));
		s.close();
	}
}

import java.util.Scanner;

class Main {

public static void main (String[] args) throws java.lang.Exception {

Scanner s = new Scanner(System.in);

int x = s.nextInt();

int y = s.nextInt();

System.out.println("Maximum number is: " + (x > y? x : y));

s.close();

}

Number of operation

14/07/2015 by Valeriya Rud

Задача Определите количество операций сложения (+), вычитания (-) и умножения (*) в арифметическом выражении заданном строкой символов.
Протестировать задачу можно здесь.

java@Cat

Учебные материалы по изучению основ языка програvмирования Java

Author Archives: Valeriya Rud

Immutable fractions

Задание

Решение

Wallpainter

Task

Input:

Output:

Tests

Solution

Between two values

Task

Tests

Solution

Find the maximum of three numbers

Tests

Solution

Find the minimum of two numbers

Tests

Solution

Code refactoring

Matrix Transpose

Транспонирование матрицы

Three flowers

Входные данные

Выходные данные

Тесты

Решение

Find the minimum of three numbers

Tests

Solution

Find the maximum of two numbers

Tests

Solution

Number of operation