[Hacker Rank]: Warmup: A Very Big Sum. Solved ✅.

Author: Gonzalo Diaz

docs/hackerrank/warmup/a_very_big_sum.md

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+# [A Very Big Sum](https://www.hackerrank.com/challenges/a-very-big-sum)
+
+Difficulty: #easy
+Category: #warmup
+
+In this challenge, you are required to calculate and print the
+sum of the elements in an array, keeping in mind that some of
+those integers may be quite large.
+
+## Function Description
+
+Complete the aVeryBigSum function in the editor below.
+It must return the sum of all array elements.
+
+aVeryBigSum has the following parameter(s):
+
+- int ar[n]: an array of integers.
+
+## Return
+
+- long: the sum of all array elements
+
+## Input Format
+
+The first line of the input consists of an integer n.
+The next line contains  space-separated integers contained in the array.
+
+## Output Format
+
+Return the integer sum of the elements in the array.
+
+## Constraints
+
+$ 1 <= n < 10 $ \
+$ 0 <= ar[i] <= 10^10 $
+
+## Sample Input
+
+```text
+5
+1000000001 1000000002 1000000003 1000000004 1000000005
+```
+
+## Output
+
+```text
+5000000015
+```
+
+## Note
+
+The range of the 32-bit integer is
+($ -2^31 $) to ($ 2^31 - 1 $) or $ [-2147483648, 2147483647] $
+When we add several integer values, the resulting sum might exceed the
+above range. You might need to use long int C/C++/Java to store such sums.

src/lib/exercises/include/exercises/hackerrank/warmup/a_very_big_sum.hpp

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+#include <vector>
+
+#pragma once
+
+namespace hackerrank::warmup {
+    long aVeryBigSum(const std::vector<long>& ar);
+}

src/lib/exercises/src/hackerrank/warmup/a_very_big_sum.cpp

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+#include <exercises/hackerrank/warmup/a_very_big_sum.hpp>
+
+/**
+ * @link Problem definition [[docs/hackerrank/warmup/a_very_big_sum.md]]
+ */
+
+#include <numeric>
+#include <vector>
+
+namespace hackerrank::warmup {
+
+    long aVeryBigSum(const std::vector<long>& ar) {
+        const long INIT_VALUE = 0L;
+        return std::accumulate(ar.begin(), ar.end(), INIT_VALUE);
+    }
+
+}

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

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+#include <catch2/catch_test_macros.hpp>
+
+#include <exercises/hackerrank/warmup/a_very_big_sum.hpp>
+#include <iostream>
+#include <vector>
+
+#include <filesystem>
+#include <fstream>
+#include <nlohmann/json.hpp>
+using json = nlohmann::json;
+
+TEST_CASE("aVeryBigSum JSON Test Cases", "[warmup]")
+{
+    std::filesystem::path cwd = std::filesystem::current_path();
+    std::string path = cwd.string() + "/unit/lib/hackerrank/warmup/a_very_big_sum.testcases.json";
+
+    INFO("aVeryBigSum JSON test cases FILE: " << path);
+
+    std::ifstream f(path);
+    json data = json::parse(f);
+
+    for (auto testcase : data) {
+        long result = hackerrank::warmup::aVeryBigSum(testcase["input"]);
+        CHECK(result == testcase["expected"]);
+    }
+}

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

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+[
+  {
+    "input": [1000000001, 1000000002, 1000000003, 1000000004, 1000000005],
+    "expected": 5000000015
+  }
+]