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

src/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 $.

src/hackerrank/projecteuler/euler002.py

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+# pylint: disable=C0103:invalid-name
+
+def fibo_even_sum(n: int) -> int:
+    total = 0
+    fibo = 0
+    fibo1 = 1
+    fibo2 = 1
+
+    while fibo1 + fibo2 < n:
+        fibo = fibo1 + fibo2
+        fibo1 = fibo2
+        fibo2 = fibo
+
+        if fibo % 2 == 0:
+            total += fibo
+
+    return total
+
+
+def euler002(n: int) -> int:
+
+    return fibo_even_sum(n)

src/hackerrank/projecteuler/euler002_test.py

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+import unittest
+from .euler002 import euler002
+
+
+class TestEuler001(unittest.TestCase):
+
+    def test_euler001(self):
+
+        tests = [
+          {'n': 10, 'answer': 10},
+          {'n': 100, 'answer': 44}
+        ]
+
+        for _, _tt in enumerate(tests):
+
+            self.assertEqual(
+                euler002(_tt['n']), _tt['answer'],
+                f"{_} | euler001({_tt['n']}) must be "
+                f"=> {_tt['answer']}")