Feature/plus minus

docs/hackerrank/warmup/plus_minus.md

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+# [Plus Minus](https://www.hackerrank.com/challenges/plus-minus)
+
+Difficulty: #easy
+Category: #warmup
+
+Given an array of integers, calculate the ratios of its elements
+that are positive, negative, and zero. Print the decimal value of
+each fraction on a new line with 6 places after the decimal.
+
+**Note**: This challenge introduces precision problems.
+The test cases are scaled to six decimal places, though answers
+with absolute error of up to $ 10^{-4} $ are acceptable.
+
+## Example
+
+$ arr = [1, 1, 0, -1, -1] $
+
+There are $ n = 5 $ elements, two positive, two negative and one zero.
+Their ratios are $ 2/5 = 0.400000 $, $ 2/5 = 0.400000 $ and $ 1/5 = 0.200000 $.
+Results are printed as:
+
+```text
+0.400000
+0.400000
+0.200000
+```
+
+## Function Description
+
+Complete the plusMinus function in the editor below.
+plusMinus has the following parameter(s):
+
+- int arr[n]: an array of integers
+
+## Print
+
+Print the ratios of positive, negative and zero values in the array.
+Each value should be printed on a separate line with $ 6 $ digits after
+the decimal. The function should not return a value.
+
+## Input Format
+
+The first line contains an integer, `n`, the size of the array.
+The second line contains `n` space-separated integers that describe `arr[n]`.
+
+## Constraints
+
+$ 0 < n \leq 100 $ \
+$ -100 \leq arr[i] \leq 100 $
+
+## Output Format
+
+**Print** the following  lines, each to  decimals:
+
+1. proportion of positive values
+2. proportion of negative values
+3. proportion of zeros
+
+## Sample Input
+
+```text
+STDIN           Function
+-----           --------
+6               arr[] size n = 6
+-4 3 -9 0 4 1   arr = [-4, 3, -9, 0, 4, 1]
+```
+
+## Sample Output
+
+```text
+0.500000
+0.333333
+0.166667
+```
+
+## Explanation
+
+There are $ 3 $ positive numbers, negative numbers, and $ 1 $ zero in the array.
+The proportions of occurrence are positive: $ 3/6 = 0.500000 $,
+negative: $ 2/6 = 0.333333 $ and zeros: $ 1/6 = 0.166667 $.

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

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+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+const int HACKERRANK_WARMUP_PLUSMINUS_LIMIT_ANSWERS = 3;
+
+char **HACKERRANK_WARMUP_plusMinusCalculate(int arr_count, const int *arr);
+void HACKERRANK_WARMUP_plusMinus(int arr_count, const int *arr);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif

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

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+#include <exercises/hackerrank/warmup/plus_minus.h>
+
+/**
+ * @link Problem definition [[docs/hackerrank/warmup/plus_minus.md]]
+ */
+
+#include <stdio.h>  // malloc
+#include <stdlib.h> // snprintf
+
+const int BUFFER_MAX_SIZE = 10;
+
+char *format_result(double number) {
+  char *buffer = malloc(BUFFER_MAX_SIZE * sizeof(char));
+
+  snprintf(buffer, BUFFER_MAX_SIZE, "%0.6lf", number);
+  return buffer;
+}
+
+char **HACKERRANK_WARMUP_plusMinusCalculate(int arr_count, const int *arr) {
+  int positives = 0;
+  int negatives = 0;
+  int zeros = 0;
+
+  int i = 0;
+
+  while (i < arr_count) {
+    int value = arr[i];
+
+    if (value > 0) {
+      positives += 1;
+    }
+    if (value < 0) {
+      negatives += 1;
+    }
+    if (value == 0) {
+      zeros += 1;
+    }
+
+    i += 1;
+  }
+
+  double const results[3] = {(double)positives / arr_count,
+                             (double)negatives / arr_count,
+                             (double)zeros / arr_count};
+
+  int n = 3; // Número de strings (puede ser arbitrario)
+  char **answer = malloc(n * sizeof(char *)); // Array de punteros
+
+  for (i = 0; i < n; i++) {
+    char *formatted = format_result(results[i]);
+    answer[i] = formatted;
+  }
+
+  return answer;
+}
+
+void HACKERRANK_WARMUP_plusMinus(int arr_count, const int *arr) {
+  char **output = HACKERRANK_WARMUP_plusMinusCalculate(arr_count, arr);
+
+  for (int i = 0; i < HACKERRANK_WARMUP_PLUSMINUS_LIMIT_ANSWERS; i++) {
+    printf("%s", output[i]);
+    free(output[i]);
+  }
+
+  free(output);
+}

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

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+#include <catch2/catch_test_macros.hpp>
+
+#include <exercises/hackerrank/warmup/plus_minus.h>
+#include <iostream>
+#include <stdexcept>
+#include <vector>
+
+#include <filesystem>
+#include <fstream>
+#include <nlohmann/json.hpp>
+using json = nlohmann::json;
+
+TEST_CASE("plusMinus JSON Test Cases", "[hackerrank] [jsontestcase] [warmup]") {
+  std::filesystem::path cwd = std::filesystem::current_path();
+  std::string path =
+      cwd.string() + "/unit/lib/hackerrank/warmup/plus_minus.testcases.json";
+
+  INFO("plusMinus JSON test cases FILE: " << path);
+
+  std::ifstream f(path);
+  json data = json::parse(f);
+
+  for (auto testcase : data) {
+    auto input_size = static_cast<int>(testcase["input"].size());
+    std::vector<int> input_vector = testcase["input"];
+    const int *input_array = input_vector.data();
+
+    char **result =
+        HACKERRANK_WARMUP_plusMinusCalculate(input_size, input_array);
+
+    std::vector<std::string> result_as_vector;
+
+    for (int i = 0; i < HACKERRANK_WARMUP_PLUSMINUS_LIMIT_ANSWERS; i++) {
+      result_as_vector.emplace_back(result[i]);
+      free(result[i]);
+    }
+    free(result);
+
+    CHECK(result_as_vector == testcase["expected"]);
+
+    // Just call void function, to collect coverage
+    HACKERRANK_WARMUP_plusMinus(input_size, input_array);
+  }
+}

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

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+[
+  {
+    "title": "test case 0",
+    "input": [-4, 3, -9, 0, 4, 1],
+    "expected": ["0.500000", "0.333333", "0.166667"]
+  }
+]