[Hacker Rank]: Warmup. Staircase solved ✅.

Author: Gonzalo Diaz

docs/hackerrank/warmup/staircase.md

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+# [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 $.

src/lib/exercises/include/exercises/hackerrank/warmup/staircase.h

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+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+char **HACKERRANK_WARMUP_staircaseCalculate(int n);
+void HACKERRANK_WARMUP_staircase(int n);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif

src/lib/exercises/src/hackerrank/warmup/staircase.c

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+#include <exercises/hackerrank/warmup/staircase.h>
+
+/**
+ * @link Problem definition [[docs/hackerrank/warmup/staircase.md]]
+ */
+
+#include <stdio.h>  // malloc
+#include <stdlib.h> // snprintf
+
+char **HACKERRANK_WARMUP_staircaseCalculate(int n) {
+
+  char **answer = malloc(n * sizeof(char *)); // Array of char pointers
+
+  for (int i = 0; i < n; i++) {
+    char *line = malloc((n + 1) * sizeof(char)); // Array of char values
+
+    for (int j = 0; j < n; j++) {
+      if (j < n - i - 1) {
+        line[j] = ' ';
+      } else {
+        line[j] = '#';
+      }
+    }
+    line[n] = '\0';
+
+    answer[i] = line;
+  }
+
+  return answer;
+}
+
+void HACKERRANK_WARMUP_staircase(int n) {
+  char **output = HACKERRANK_WARMUP_staircaseCalculate(n);
+
+  for (int i = 0; i < n; i++) {
+    printf("%s\n", output[i]);
+    free(output[i]);
+  }
+
+  free(output);
+}

src/tests/unit/lib/hackerrank/warmup/staircase.test.cpp

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+#include <catch2/catch_test_macros.hpp>
+
+#include <exercises/hackerrank/warmup/staircase.h>
+#include <filesystem>
+#include <fstream>
+#include <nlohmann/json.hpp>
+#include <vector>
+
+using json = nlohmann::json;
+
+TEST_CASE("staircase", "[warmup]") {
+  std::filesystem::path cwd = std::filesystem::current_path();
+  std::string path =
+      cwd.string() + "/unit/lib/hackerrank/warmup/staircase.testcases.json";
+
+  INFO("staircase JSON test cases FILE: " << path);
+
+  std::ifstream f(path);
+  json data = json::parse(f);
+
+  for (auto testcase : data) {
+    auto input = static_cast<int>(testcase["input"]);
+
+    char **result = HACKERRANK_WARMUP_staircaseCalculate(input);
+
+    std::vector<std::string> result_as_vector;
+
+    for (int i = 0; i < input; i++) {
+      result_as_vector.emplace_back(result[i]);
+    }
+
+    CHECK(result_as_vector == testcase["expected"]);
+
+    // Just call void function, to collect coverage
+    HACKERRANK_WARMUP_staircase(input);
+  }
+}

src/tests/unit/lib/hackerrank/warmup/staircase.testcases.json

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+[
+  {
+    "input": 6,
+    "expected": ["     #", "    ##", "   ###", "  ####", " #####", "######"]
+  }
+]