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Refactor ReverseNumber (#4208)
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@ -1,30 +1,31 @@
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package com.thealgorithms.maths;
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package com.thealgorithms.maths;
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import java.lang.IllegalStateException;
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import java.lang.IllegalArgumentException;
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import java.util.NoSuchElementException;
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import java.util.Scanner;
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public class ReverseNumber {
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/**
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* @brief utility class reversing numbers
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*/
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final public class ReverseNumber {
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private ReverseNumber() {
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}
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public static void main(String[] args) {
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/**
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int number;
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* @brief reverses the input number
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int reverse = 0;
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* @param number the input number
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* @exception IllegalArgumentException number is negative
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try (Scanner sc = new Scanner(System.in)) {
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* @return the number created by reversing the order of digits of the input number
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System.out.println("Enter a number:");
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*/
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number = sc.nextInt();
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public static int reverseNumber(int number) {
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} catch (NoSuchElementException | IllegalStateException e) {
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if (number < 0) {
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System.out.println("ERROR: Invalid input");
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throw new IllegalArgumentException("number must be nonnegative.");
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return;
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}
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}
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while (number != 0) {
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int result = 0;
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int remainder = number % 10;
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while (number > 0) {
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result *= 10;
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reverse = reverse * 10 + remainder;
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result += number % 10;
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number = number / 10;
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number /= 10;
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}
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}
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return result;
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System.out.println("The reverse of the given number is: " + reverse);
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}
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}
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}
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}
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33
src/test/java/com/thealgorithms/maths/ReverseNumberTest.java
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33
src/test/java/com/thealgorithms/maths/ReverseNumberTest.java
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@ -0,0 +1,33 @@
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package com.thealgorithms.maths;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import static org.junit.jupiter.api.Assertions.assertThrows;
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import java.util.HashMap;
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import org.junit.jupiter.api.Test;
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public class ReverseNumberTest {
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@Test
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public void testReverseNumber() {
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HashMap<Integer, Integer> testCases = new HashMap<>();
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testCases.put(0, 0);
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testCases.put(1, 1);
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testCases.put(10, 1);
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testCases.put(123, 321);
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testCases.put(7890, 987);
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for (final var tc : testCases.entrySet()) {
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assertEquals(ReverseNumber.reverseNumber(tc.getKey()), tc.getValue());
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}
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}
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@Test
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public void testReverseNumberThrowsExceptionForNegativeInput() {
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assertThrows(
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IllegalArgumentException.class,
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() -> ReverseNumber.reverseNumber(-1)
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);
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}
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}
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