[Hacker Rank] Warm up: Staircase solved ✓

algorithm-exercises-java/src/main/java/ae/hackerrank/warmup/Staircase.java

@@ -0,0 +1,39 @@
+package ae.hackerrank.warmup;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Staricase.
+ *
+ * @link Problem definition [[docs/hackerrank/warmup/staircase.md]]
+ */
+public class Staircase {
+
+  private Staircase() {
+  }
+
+  static java.util.logging.Logger logger = util.CustomLogger.getLogger();
+
+  /**
+   * staircase.
+   */
+  public static String staircase(int n) {
+    List<String> result = new ArrayList<>();
+
+    for (int i = 1; i < n + 1; i++) {
+      StringBuilder line = new StringBuilder();
+
+      for (int j = 1; j < n + 1; j++) {
+        if (j <= n - i) {
+          line.append(" ");
+        } else {
+          line.append("#");
+        }
+      }
+
+      result.add(line.toString());
+    }
+    return String.join("\n", result);
+  }
+}

algorithm-exercises-java/src/test/java/ae/hackerrank/warmup/StaircaseTest.java

@@ -0,0 +1,51 @@
+package ae.hackerrank.warmup;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Arrays;
+import java.util.List;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.api.TestInstance.Lifecycle;
+
+@TestInstance(Lifecycle.PER_CLASS)
+class StaircaseTest {
+  public class StaircaseTestCase {
+    public Integer input;
+    public String expected;
+
+    public StaircaseTestCase(Integer _input, String _expected) {
+      this.input = _input;
+      this.expected = _expected;
+    }
+  }
+
+  public List<StaircaseTestCase> testCases;
+
+  @BeforeAll
+  public void setup() {
+    this.testCases = Arrays.asList(
+        new StaircaseTestCase(
+            6, String.join("\n",
+                "     #",
+                "    ##",
+                "   ###",
+                "  ####",
+                " #####",
+                "######")));
+  }
+
+  @Test
+  void testStaircase() {
+    for (StaircaseTestCase testCase : this.testCases) {
+      String solutionFound = Staircase.staircase(testCase.input);
+
+      assertEquals(testCase.expected, solutionFound,
+          String.format("%s(%d) answer must be: %s",
+              "Staircase.staircase",
+              testCase.input,
+              testCase.expected));
+    }
+  }
+}

docs/hackerrank/warmup/staircase.md

@@ -0,0 +1,67 @@
+# [Staircase](https://www.hackerrank.com/challenges/staircase)
+
+Difficulty: #easy
+Category: #warmup
+
+Staircase detail
+This is a staircase of size $ n = 4 $:
+
+```text
+   #
+  ##
+ ###
+####
+```
+
+Its base and height are both equal to n. It is drawn using # symbols
+and spaces. The last line is not preceded by any spaces.
+
+Write a program that prints a staircase of size n.
+
+## Function Description
+
+Complete the staircase function in the editor below.
+
+staircase has the following parameter(s):
+
+* int n: an integer
+
+## Print
+
+Print a staircase as described above.
+
+## Input Format
+
+A single integer, , denoting the size of the staircase.
+
+Constraints
+
+$ 0 < n \leq 100 $
+
+## Output Format
+
+Print a staircase of size n using # symbols and spaces.
+
+Note: The last line must have  spaces in it.
+
+## Sample Input
+
+```text
+6
+```
+
+## Sample Output
+
+```text
+     #
+    ##
+   ###
+  ####
+ #####
+######
+```
+
+## Explanation
+
+The staircase is right-aligned, composed of # symbols and spaces,
+and has a height and width of $ n = 6 $.