[Hacker Rank]: Project Euler #2: Even Fibonacci numbers solved ✓

algorithm-exercises-csharp/src/hackerrank/projecteuler/Euler002.Test.cs

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+namespace algorithm_exercises_csharp.hackerrank.prohecteuler;
+
+[TestClass]
+public class Euler002Test
+{
+  public class Euler002TestCase {
+    public int n; public int answer;
+  }
+
+  // dotnet_style_readonly_field = true
+  private static readonly Euler002TestCase[] tests = [
+    new() { n = 10, answer = 10},
+    new() { n = 100, answer = 44}
+  ];
+
+  [TestMethod]
+  public void Euler002ProblemTest()
+  {
+    int result;
+
+    foreach (Euler002TestCase test in tests) {
+      result = Euler002Problem.Euler002(test.n);
+        Assert.AreEqual(test.answer, result);
+    }
+  }
+}
+

algorithm-exercises-csharp/src/hackerrank/projecteuler/Euler002.cs

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+// @link Problem definition [[docs/hackerrank/projecteuler/euler002.md]]
+
+namespace algorithm_exercises_csharp.hackerrank.prohecteuler;
+
+using System.Diagnostics.CodeAnalysis;
+
+public class Euler002Problem
+{
+  [ExcludeFromCodeCoverage]
+  protected Euler002Problem() {}
+
+  public static int FiboEvenSum(int n) {
+    int total = 0;
+    int fibo;
+    int fibo1 = 1;
+    int fibo2 = 1;
+
+    while (fibo1 + fibo2 < n) {
+        fibo = fibo1 + fibo2;
+        fibo1 = fibo2;
+        fibo2 = fibo;
+
+        if(fibo % 2 == 0) {
+            total += fibo;
+        }
+    }
+
+    return total;
+  }
+
+  // Function to find the sum of all multiples of a and b below n
+  public static int Euler002(int n)
+  {
+    return FiboEvenSum(n);
+  }
+}

docs/hackerrank/projecteuler/euler002.md

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+# [Even Fibonacci numbers](https://www.hackerrank.com/contests/projecteuler/challenges/euler002)
+
+- Difficulty: #easy
+- Category: #ProjectEuler+
+
+Each new term in the Fibonacci sequence is generated by adding the previous two terms.
+By starting with $ 1 $ and $ 2 $, the first $ 10 $ terms will be:
+
+$$ 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 $$
+
+By considering the terms in the Fibonacci sequence whose values do not exceed
+$ N $, find the sum of the even-valued terms.
+
+## Input Format
+
+First line contains $ T $ that denotes the number of test cases. This is
+followed by $ T $ lines, each containing an integer, $ N $.
+
+## Constraints
+
+- $ 1 \leq T \leq 10^5 $
+- $ 10 \leq N \leq 4 × 10^{16} $
+
+## Output Format
+
+Print the required answer for each test case.
+
+## Sample Input 0
+
+```text
+2
+10
+100
+```
+
+## Sample Output 0
+
+```text
+10
+44
+```
+
+## Explanation 0
+
+- For $ N = 10 $, we have $ \{2, 8\} $, sum is $ 10 $.
+
+- For $ N = 100 $, we have $ \{2, 8, 34 \} $, sum is $ 44 $.