Project Euler: Problem 2: Even Fibonacci Numbers - fiboEvenSum(10) sh… (#34722)

curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-2-even-fibonacci-numbers.english.md

@@ -8,7 +8,7 @@ title: 'Problem 2: Even Fibonacci Numbers'
 <section id='description'>
 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:
 <div style='text-align: center;'>1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...</div>
-By considering the terms in the Fibonacci sequence whose values do not exceed <code>n</code>th term, find the sum of the even-valued terms.
+By considering the terms in the Fibonacci sequence that do not exceed the <code>n</code>th term, find the sum of the even-valued terms.
 </section>
 
 ## Instructions
@@ -21,16 +21,16 @@ By considering the terms in the Fibonacci sequence whose values do not exceed <c
 
 ```yml
 tests:
-  - text: <code>fiboEvenSum(10)</code> should return 188.
-    testString: assert.strictEqual(fiboEvenSum(10), 188, '<code>fiboEvenSum(10)</code> should return 188.');
+  - text: <code>fiboEvenSum(10)</code> should return 44.
+    testString: assert.strictEqual(fiboEvenSum(10), 44, '<code>fiboEvenSum(10)</code> should return 44.');
+  - text: <code>fiboEvenSum(18)</code> should return 3382.
+    testString: assert.strictEqual(fiboEvenSum(18), 3382, '<code>fiboEvenSum(18)</code> should return 3382.');
   - text: <code>fiboEvenSum(23)</code> should return 60696.
     testString: assert.strictEqual(fiboEvenSum(23), 60696, '<code>fiboEvenSum(23)</code> should return 60696.');
-  - text: <code>fiboEvenSum(43)</code> should return 1485607536.
-    testString: assert.strictEqual(fiboEvenSum(43), 1485607536, '<code>fiboEvenSum(43)</code> should return 1485607536.');
-  - text: Your function is not returning the correct result using our tests values.
-    testString: assert.strictEqual(fiboEvenSum(18), 3382, 'Your function is not returning the correct result using our tests values.');
+  - text: <code>fiboEvenSum(43)</code> should return 350704366.
+    testString: assert.strictEqual(fiboEvenSum(43), 350704366, '<code>fiboEvenSum(43)</code> should return 350704366.');
   - text: Your function should return an <code>even</code> value.
-    testString: assert.equal(fiboEvenSum(31) % 2 === 0, true, 'Your function should return an <code>even</code> value.');
+    testString: assert.equal(fiboEvenSum(10) % 2 === 0, true, 'Your function should return an <code>even</code> value.');
 
 ```
 
@@ -62,18 +62,20 @@ fiboEvenSum(10);
 
 ```js
 const fiboEvenSum = (number) => {
-  let temp, sum = 0, a = 0, b = 1;
-    while (number >= 0) {
-      temp = a;
-      a = b;
-      b += temp;
-      number --;
-      if ((b % 2) === 0) {
-        sum += b;
+  if (number <= 1) {
+    return 0;
+  } else {
+      let evenSum = 2, first = 1, second = 2, fibNum; // According to problem description our Fibonacci series starts with 1, 2
+      for (let i = 3; i <= number; i++) {
+        fibNum = first + second;
+        first = second;
+        second = fibNum;
+        if (fibNum % 2 == 0) {
+          evenSum += fibNum;
         }
       }
-
-  return sum;
+      return evenSum;
+  }
 }
 ```