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BAEL-1889 - Let's move the Java Number articles into a new module (#4619)

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* BAEL-1849 - Convert from String to Date in Java

* BAEL-1863 - Calling Callbacks with Mockito

* BAEL-1889 - Let's move the Java Number articles into a new module

* BAEL-1889 - Let's move the Java Number articles into a new module
This commit is contained in:
Jonathan Cook
2018-07-14 15:00:37 +02:00
committed by Grzegorz Piwowarek
parent de2afd7da8
commit b44883b364
41 changed files with 380 additions and 188 deletions
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2
algorithms/README.md
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@@ -5,7 +5,6 @@
- [Ant Colony Optimization](http://www.baeldung.com/java-ant-colony-optimization)
- [Validating Input With Finite Automata in Java](http://www.baeldung.com/java-finite-automata)
- [Introduction to Jenetics Library](http://www.baeldung.com/jenetics)
- [Check If a Number Is Prime in Java](http://www.baeldung.com/java-prime-numbers)
- [Example of Hill Climbing Algorithm](http://www.baeldung.com/java-hill-climbing-algorithm)
- [Monte Carlo Tree Search for Tic-Tac-Toe Game](http://www.baeldung.com/java-monte-carlo-tree-search)
- [String Search Algorithms for Large Texts](http://www.baeldung.com/java-full-text-search-algorithms)
@@ -21,7 +20,6 @@
- [Create a Sudoku Solver in Java](http://www.baeldung.com/java-sudoku)
- [Displaying Money Amounts in Words](http://www.baeldung.com/java-money-into-words)
- [A Collaborative Filtering Recommendation System in Java](http://www.baeldung.com/java-collaborative-filtering-recommendations)
- [Find All Pairs of Numbers in an Array That Add Up to a Given Sum](http://www.baeldung.com/java-algorithm-number-pairs-sum)
- [Converting Between Roman and Arabic Numerals in Java](http://www.baeldung.com/java-convert-roman-arabic)
- [Practical Java Examples of the Big O Notation](http://www.baeldung.com/java-algorithm-complexity)
- [Find the Middle Element of a Linked List](http://www.baeldung.com/java-linked-list-middle-element)

7
algorithms/src/main/java/com/baeldung/algorithms/RunAlgorithm.java
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@@ -6,7 +6,6 @@ import com.baeldung.algorithms.ga.annealing.SimulatedAnnealing;
import com.baeldung.algorithms.ga.ant_colony.AntColonyOptimization;
import com.baeldung.algorithms.ga.binary.SimpleGeneticAlgorithm;
import com.baeldung.algorithms.slope_one.SlopeOne;
import com.baeldung.algorithms.pairsaddupnumber.FindPairs;
public class RunAlgorithm {
@@ -39,12 +38,6 @@ public class RunAlgorithm {
case 5:
System.out.println("Please run the DijkstraAlgorithmTest.");
break;
case 6:
final FindPairs findPairs = new FindPairs();
final int[] input = {1, 4, 3, 2, 1, 4, 4, 3, 3};
final int sum = 6;
findPairs.execute(input, sum);
break;
default:
System.out.println("Unknown option");
break;

72
algorithms/src/main/java/com/baeldung/algorithms/pairsaddupnumber/DifferentPairs.java
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@@ -1,72 +0,0 @@
package com.baeldung.algorithms.pairsaddupnumber;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.IntStream;
/**
* Find all different pairs of numbers in an array that add up to a given sum - Complexity O(n)
*/
public class DifferentPairs {
/**
* Show all different pairs using traditional "for" loop
*
* @param input - number's array
* @param sum - given sum
* @return - number's array with all existing pairs. This list will contain just one pair's element because
* the other one can be calculated with SUM - element_1 = element_2
*/
public static List<Integer> findPairsWithForLoop(int[] input, int sum) {
final List<Integer> allDifferentPairs = new ArrayList<>();
// Aux. hash map
final Map<Integer, Integer> pairs = new HashMap();
for (int i : input) {
if (pairs.containsKey(i)) {
if (pairs.get(i) != null) {
// Add pair to returned list
allDifferentPairs.add(i);
}
// Mark pair as added to prevent duplicates
pairs.put(sum - i, null);
} else if (!pairs.containsValue(i)) {
// Add pair to aux. hash map
pairs.put(sum - i, i);
}
}
return allDifferentPairs;
}
/**
* Show all different pairs using Java 8 stream API
*
* @param input - number's array
* @param sum - given sum
* @return - number's array with all existing pairs. This list will contain just one pair's element because
* the other one can be calculated with SUM - element_1 = element_2
*/
public static List<Integer> findPairsWithStreamApi(int[] input, int sum) {
final List<Integer> allDifferentPairs = new ArrayList<>();
// Aux. hash map
final Map<Integer, Integer> pairs = new HashMap();
IntStream.range(0, input.length).forEach(i -> {
if (pairs.containsKey(input[i])) {
if (pairs.get(input[i]) != null) {
// Add pair to returned list
allDifferentPairs.add(input[i]);
}
// Mark pair as added to prevent duplicates
pairs.put(sum - input[i], null);
} else if (!pairs.containsValue(input[i])) {
// Add pair to aux. hash map
pairs.put(sum - input[i], input[i]);
}
}
);
return allDifferentPairs;
}
}

51
algorithms/src/main/java/com/baeldung/algorithms/pairsaddupnumber/ExistingPairs.java
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@@ -1,51 +0,0 @@
package com.baeldung.algorithms.pairsaddupnumber;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.IntStream;
/**
* Find all existing pairs of numbers in an array that add up to a given sum - Complexity O(n^2) "Brute force"
*/
public class ExistingPairs {
/**
* Show all existing pairs using traditional "for" loop
*
* @param input - number's array
* @param sum - given sum
* @return - number's array with all existing pairs. This list will contain just one pair's element because
* the other one can be calculated with SUM - element_1 = element_2
*/
public static List<Integer> findPairsWithForLoop(int[] input, int sum) {
final List<Integer> allExistingPairs = new ArrayList<>();
for (int i = 0; i < input.length; i++) {
for (int j = 0; j < input.length; j++) {
if (j != i && (input[i] + input[j]) == sum) {
allExistingPairs.add(input[i]);
}
}
}
return allExistingPairs;
}
/**
* Show all existing pairs using Java 8 stream API
*
* @param input - number's array
* @param sum - given sum
* @return - number's array with all existing pairs. This list will contain just one pair's element because
* the other one can be calculated with SUM - element_1 = element_2
*/
public static List<Integer> findPairsWithStreamApi(int[] input, int sum) {
final List<Integer> allExistingPairs = new ArrayList<>();
IntStream.range(0, input.length).forEach(i ->
IntStream.range(0, input.length)
.filter(j -> i != j && input[i] + input[j] == sum)
.forEach(j -> allExistingPairs.add(input[i]))
);
return allExistingPairs;
}
}

74
algorithms/src/main/java/com/baeldung/algorithms/pairsaddupnumber/FindPairs.java
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@@ -1,74 +0,0 @@
package com.baeldung.algorithms.pairsaddupnumber;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.IntStream;
public class FindPairs {
public void execute(int[] input, int sum) {
final StringBuilder inputArray = new StringBuilder();
inputArray.append("{");
IntStream.range(0, input.length).forEach(i -> inputArray.append(input[i] + ", "));
inputArray.append("}");
System.out.println(" Given number array: " + inputArray.toString());
System.out.println(" Given sum: " + sum);
/* Call services */
getDifferentPairs(input, sum);
getExistingPairs(input, sum);
}
/**
* Print all existing pairs for the given inputs: input array & sum number
*/
private static void getExistingPairs(int[] input, int sum) {
List<Integer> pairs = new ArrayList<>();
System.out.println("~ All existing pairs ~");
/* Traditional FOR loop */
// Call method
pairs = ExistingPairs.findPairsWithForLoop(input, sum);
// Create a pretty printing
final StringBuilder output1 = new StringBuilder();
pairs.forEach((pair) -> output1.append("{" + pair + ", " + (sum - pair) + "}, "));
// Print result
System.out.println("Traditional \"for\" loop: " + output1.toString().substring(0, output1.length() - 2));
/* Java 8 stream API */
// Call the method
pairs = ExistingPairs.findPairsWithStreamApi(input, sum);
// Create a pretty printing
final StringBuilder output2 = new StringBuilder();
pairs.forEach((pair) -> output2.append("{" + pair + ", " + (sum - pair) + "}, "));
// Print result
System.out.println("Java 8 streams API: " + output2.toString().substring(0, output2.length() - 2));
}
/**
* Print all different pairs for the given inputs: input array & sum number
*/
private static void getDifferentPairs(int[] input, int sum) {
List<Integer> pairs = new ArrayList<>();
System.out.println("~ All different pairs ~");
/* Traditional FOR loop */
// Call method
pairs = DifferentPairs.findPairsWithForLoop(input, sum);
// Create a pretty printing
final StringBuilder output3 = new StringBuilder();
pairs.forEach((pair) -> output3.append("{" + pair + ", " + (sum - pair) + "}, "));
// Print result
System.out.println("Traditional \"for\" loop: " + output3.toString().substring(0, output3.length() - 2));
/* Java 8 stream API */
// Call method
pairs = DifferentPairs.findPairsWithStreamApi(input, sum);
// Create a pretty printing
final StringBuilder output4 = new StringBuilder();
pairs.forEach((pair) -> output4.append("{" + pair + ", " + (sum - pair) + "}, "));
// Print result
System.out.println("Java 8 streams API: " + output4.toString().substring(0, output4.length() - 2));
}
}

59
algorithms/src/main/java/com/baeldung/algorithms/prime/PrimeGenerator.java
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@@ -1,59 +0,0 @@
package com.baeldung.algorithms.prime;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
public class PrimeGenerator {
public static List<Integer> sieveOfEratosthenes(int n) {
final boolean prime[] = new boolean[n + 1];
Arrays.fill(prime, true);
for (int p = 2; p * p <= n; p++) {
if (prime[p]) {
for (int i = p * 2; i <= n; i += p)
prime[i] = false;
}
}
final List<Integer> primes = new LinkedList<>();
for (int i = 2; i <= n; i++) {
if (prime[i])
primes.add(i);
}
return primes;
}
public static List<Integer> primeNumbersBruteForce(int max) {
final List<Integer> primeNumbers = new LinkedList<Integer>();
for (int i = 2; i <= max; i++) {
if (isPrimeBruteForce(i)) {
primeNumbers.add(i);
}
}
return primeNumbers;
}
private static boolean isPrimeBruteForce(int x) {
for (int i = 2; i < x; i++) {
if (x % i == 0) {
return false;
}
}
return true;
}
public static List<Integer> primeNumbersTill(int max) {
return IntStream.rangeClosed(2, max)
.filter(x -> isPrime(x))
.boxed()
.collect(Collectors.toList());
}
private static boolean isPrime(int x) {
return IntStream.rangeClosed(2, (int) (Math.sqrt(x)))
.allMatch(n -> x % n != 0);
}
}

13
algorithms/src/main/java/com/baeldung/algorithms/primechecker/BigIntegerPrimeChecker.java
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@@ -1,13 +0,0 @@
package com.baeldung.algorithms.primechecker;
import java.math.BigInteger;
public class BigIntegerPrimeChecker implements PrimeChecker<Long>{
@Override
public boolean isPrime(Long number) {
BigInteger bigInt = BigInteger.valueOf(number);
return bigInt.isProbablePrime(100);
}
}

16
algorithms/src/main/java/com/baeldung/algorithms/primechecker/BruteForcePrimeChecker.java
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@@ -1,16 +0,0 @@
package com.baeldung.algorithms.primechecker;
import java.util.stream.IntStream;
import java.util.stream.LongStream;
public class BruteForcePrimeChecker implements PrimeChecker<Integer>{
@Override
public boolean isPrime(Integer number) {
return number > 2 ? IntStream.range(2, number)
.noneMatch(n -> (number % n == 0)) : false;
}
}

15
algorithms/src/main/java/com/baeldung/algorithms/primechecker/OptimisedPrimeChecker.java
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@@ -1,15 +0,0 @@
package com.baeldung.algorithms.primechecker;
import java.util.stream.IntStream;
import java.util.stream.LongStream;
public class OptimisedPrimeChecker implements PrimeChecker<Integer>{
@Override
public boolean isPrime(Integer number) {
return number > 2 ? IntStream.rangeClosed(2, (int) Math.sqrt(number))
.noneMatch(n -> (number % n == 0)) : false;
}
}

6
algorithms/src/main/java/com/baeldung/algorithms/primechecker/PrimeChecker.java
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@@ -1,6 +0,0 @@
package com.baeldung.algorithms.primechecker;
public interface PrimeChecker <T> {
public boolean isPrime( T number );
}

12
algorithms/src/main/java/com/baeldung/algorithms/primechecker/PrimesPrimeChecker.java
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@@ -1,12 +0,0 @@
package com.baeldung.algorithms.primechecker;
import org.apache.commons.math3.primes.Primes;
public class PrimesPrimeChecker implements PrimeChecker<Integer>{
@Override
public boolean isPrime(Integer number) {
return Primes.isPrime(number);
}
}

39
algorithms/src/test/java/com/baeldung/algorithms/pairsaddupnumber/DifferentPairsUnitTest.java
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@@ -1,39 +0,0 @@
package com.baeldung.algorithms.pairsaddupnumber;
import org.junit.Test;
import java.util.List;
import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
public class DifferentPairsUnitTest {
/* All different pairs */
@Test
public void whenTraditionalLoop_thenReturnAllDifferentPairs() {
/* Data */
final int[] input = {2, 4, 3, 3, 8};
final int sum = 6;
/* Call service */
final List<Integer> pairs = DifferentPairs.findPairsWithForLoop(input, sum);
/* Check results */
assertThat(pairs).hasSize(2).contains(4,3).doesNotContain(8);
}
@Test
public void whenStreamApi_thenReturnAllDifferentPairs() {
/* Data */
final int[] input = {2, 4, 3, 3, 8};
final int sum = 6;
/* Call service */
final List<Integer> pairs = DifferentPairs.findPairsWithStreamApi(input, sum);
/* Check results */
assertNotNull(pairs);
assertEquals(pairs.size(),2);
assertEquals(pairs.get(0), new Integer(4));
assertThat(pairs).hasSize(2).contains(4,3).doesNotContain(8);
}
}

34
algorithms/src/test/java/com/baeldung/algorithms/pairsaddupnumber/ExistingPairsUnitTest.java
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@@ -1,34 +0,0 @@
package com.baeldung.algorithms.pairsaddupnumber;
import org.junit.Test;
import java.util.List;
import static org.assertj.core.api.Assertions.assertThat;
public class ExistingPairsUnitTest {
/* All existing pairs */
@Test
public void whenTraditionalLoop_thenReturnAllExistingPairs() {
/* Data */
final int[] input = {2, 4, 3, 3, 8};
final int sum = 6;
/* Call service */
final List<Integer> pairs = ExistingPairs.findPairsWithForLoop(input, sum);
/* Check results */
assertThat(pairs).hasSize(4).contains(2,4,3,3).doesNotContain(8);
}
@Test
public void whenStreamApi_thenReturnAllExistingPairs() {
/* Data */
final int[] input = {2, 4, 3, 3, 8};
final int sum = 6;
/* Call service */
final List<Integer> pairs = ExistingPairs.findPairsWithStreamApi(input, sum);
/* Check results */
assertThat(pairs).hasSize(4).contains(2,4,3,3).doesNotContain(8);
}
}

28
algorithms/src/test/java/com/baeldung/algorithms/prime/PrimeGeneratorUnitTest.java
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@@ -1,28 +0,0 @@
package com.baeldung.algorithms.prime;
import static com.baeldung.algorithms.prime.PrimeGenerator.*;
import java.util.Arrays;
import java.util.List;
import org.junit.Test;
import static org.junit.Assert.*;
public class PrimeGeneratorUnitTest {
@Test
public void whenBruteForced_returnsSuccessfully() {
final List<Integer> primeNumbers = primeNumbersBruteForce(20);
assertEquals(Arrays.asList(new Integer[] { 2, 3, 5, 7, 11, 13, 17, 19 }), primeNumbers);
}
@Test
public void whenOptimized_returnsSuccessfully() {
final List<Integer> primeNumbers = primeNumbersTill(20);
assertEquals(Arrays.asList(new Integer[] { 2, 3, 5, 7, 11, 13, 17, 19 }), primeNumbers);
}
@Test
public void whenSieveOfEratosthenes_returnsSuccessfully() {
final List<Integer> primeNumbers = sieveOfEratosthenes(20);
assertEquals(Arrays.asList(new Integer[] { 2, 3, 5, 7, 11, 13, 17, 19 }), primeNumbers);
}
}

69
algorithms/src/test/java/com/baeldung/algorithms/primechecker/PrimeCheckerUnitTest.java
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@@ -1,69 +0,0 @@
package com.baeldung.algorithms.primechecker;
import org.junit.Test;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
public class PrimeCheckerUnitTest {
private final BigIntegerPrimeChecker primeChecker = new BigIntegerPrimeChecker();
@Test
public void whenCheckIsPrime_thenTrue(){
assertTrue(primeChecker.isPrime(13l));
assertTrue(primeChecker.isPrime(1009L));
assertTrue(primeChecker.isPrime(74207281L));
}
@Test
public void whenCheckIsPrime_thenFalse(){
assertTrue(!primeChecker.isPrime(50L));
assertTrue(!primeChecker.isPrime(1001L));
assertTrue(!primeChecker.isPrime(74207282L));
}
private final BruteForcePrimeChecker bfPrimeChecker = new BruteForcePrimeChecker();
@Test
public void whenBFCheckIsPrime_thenTrue(){
assertTrue(bfPrimeChecker.isPrime(13));
assertTrue(bfPrimeChecker.isPrime(1009));
}
@Test
public void whenBFCheckIsPrime_thenFalse(){
assertFalse(bfPrimeChecker.isPrime(50));
assertFalse(bfPrimeChecker.isPrime(1001));
}
private final OptimisedPrimeChecker optimisedPrimeChecker = new OptimisedPrimeChecker();
@Test
public void whenOptCheckIsPrime_thenTrue(){
assertTrue(optimisedPrimeChecker.isPrime(13));
assertTrue(optimisedPrimeChecker.isPrime(1009));
}
@Test
public void whenOptCheckIsPrime_thenFalse(){
assertFalse(optimisedPrimeChecker.isPrime(50));
assertFalse(optimisedPrimeChecker.isPrime(1001));
}
private final PrimesPrimeChecker primesPrimeChecker = new PrimesPrimeChecker();
@Test
public void whenPrimesCheckIsPrime_thenTrue() {
assertTrue(primesPrimeChecker.isPrime(13));
assertTrue(primesPrimeChecker.isPrime(1009));
}
@Test
public void whenPrimesCheckIsPrime_thenFalse() {
assertFalse(primesPrimeChecker.isPrime(50));
assertFalse(primesPrimeChecker.isPrime(1001));
}
}