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catalin-burceaKevinGilmore
catalin-burcea
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KevinGilmore
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create triangles with for loops - examples (eugenp#7513)
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‎algorithms-miscellaneous-3/pom.xml‎

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<artifactId>guava</artifactId>
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<version>${guava.version}</version>
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</dependency>
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<dependency>
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<groupId>org.apache.commons</groupId>
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<artifactId>commons-lang3</artifactId>
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<version>3.8.1</version>
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</dependency>
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<dependency>
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<groupId>pl.pragmatists</groupId>
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<artifactId>JUnitParams</artifactId>
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<version>1.1.0</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<build>

‎algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/printtriangles/PrintTriangleExamples.java‎

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package com.baeldung.algorithms.printtriangles;
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import org.apache.commons.lang3.StringUtils;
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public class PrintTriangleExamples {
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public static String printARightAngledTriangle(int N) {
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StringBuilder result = new StringBuilder();
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for (int r = 1; r <= N; r++) {
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for (int j = 1; j <= r; j++) {
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result.append("*");
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}
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result.append(System.lineSeparator());
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}
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return result.toString();
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}
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public static String printAnIsoscelesTriangle(int N) {
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StringBuilder result = new StringBuilder();
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for (int r = 1; r <= N; r++) {
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for (int sp = 1; sp <= N - r; sp++) {
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result.append(" ");
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}
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for (int c = 1; c <= (r * 2) - 1; c++) {
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result.append("*");
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}
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result.append(System.lineSeparator());
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}
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return result.toString();
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}
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public static String printAnIsoscelesTriangleUsingSubstring(int N) {
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StringBuilder result = new StringBuilder();
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String helperString = StringUtils.repeat(' ', N - 1) + StringUtils.repeat('*', N * 2 - 1);
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for (int r = 0; r < N; r++) {
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result.append(helperString.substring(r, N + 2 * r));
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result.append(System.lineSeparator());
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}
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return result.toString();
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}
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public static void main(String[] args) {
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System.out.println(printARightAngledTriangle(5));
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System.out.println(printAnIsoscelesTriangle(5));
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System.out.println(printAnIsoscelesTriangleUsingSubstring(5));
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}
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}

‎algorithms-miscellaneous-3/src/test/java/com/baeldung/algorithms/printtriangles/PrintTriangleExamplesUnitTest.java‎

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package com.baeldung.algorithms.printtriangles;
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import junitparams.JUnitParamsRunner;
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import junitparams.Parameters;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import static org.junit.Assert.assertEquals;
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@RunWith(JUnitParamsRunner.class)
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public class PrintTriangleExamplesUnitTest {
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private static Object[][] rightAngledTriangles() {
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String expected0 = "";
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String expected2 = "*" + System.lineSeparator()
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+ "**" + System.lineSeparator();
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String expected5 = "*" + System.lineSeparator()
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+ "**" + System.lineSeparator()
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+ "***" + System.lineSeparator()
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+ "****" + System.lineSeparator()
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+ "*****" + System.lineSeparator();
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String expected7 = "*" + System.lineSeparator()
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+ "**" + System.lineSeparator()
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+ "***" + System.lineSeparator()
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+ "****" + System.lineSeparator()
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+ "*****" + System.lineSeparator()
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+ "******" + System.lineSeparator()
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+ "*******" + System.lineSeparator();
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return new Object[][] {
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{ 0, expected0 },
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{ 2, expected2 },
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{ 5, expected5 },
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{ 7, expected7 }
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};
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}
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@Test
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@Parameters(method = "rightAngledTriangles")
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public void whenPrintARightAngledTriangleIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {
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String actual = PrintTriangleExamples.printARightAngledTriangle(nrOfRows);
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assertEquals(expected, actual);
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}
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private static Object[][] isoscelesTriangles() {
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String expected0 = "";
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String expected2 = " *" + System.lineSeparator()
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+ "***" + System.lineSeparator();
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String expected5 = " *" + System.lineSeparator()
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+ " ***" + System.lineSeparator()
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+ " *****" + System.lineSeparator()
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+ " *******" + System.lineSeparator()
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+ "*********" + System.lineSeparator();
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String expected7 = " *" + System.lineSeparator()
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+ " ***" + System.lineSeparator()
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+ " *****" + System.lineSeparator()
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+ " *******" + System.lineSeparator()
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+ " *********" + System.lineSeparator()
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+ " ***********" + System.lineSeparator()
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+ "*************" + System.lineSeparator();
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return new Object[][] {
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{ 0, expected0 },
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{ 2, expected2 },
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{ 5, expected5 },
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{ 7, expected7 }
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};
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}
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@Test
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@Parameters(method = "isoscelesTriangles")
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public void whenPrintAnIsoscelesTriangleIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {
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String actual = PrintTriangleExamples.printAnIsoscelesTriangle(nrOfRows);
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assertEquals(expected, actual);
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}
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@Test
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@Parameters(method = "isoscelesTriangles")
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public void whenPrintAnIsoscelesTriangleUsingSubstringIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {
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String actual = PrintTriangleExamples.printAnIsoscelesTriangleUsingSubstring(nrOfRows);
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assertEquals(expected, actual);
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}
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}

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