From 8a858b470ceb60d5421b5279a58ac3eb3a3f3625 Mon Sep 17 00:00:00 2001
From: Rostyslav Ugryniuk <ug.ross@hotmail.com>
Date: Thu, 7 May 2020 21:31:59 +0300
Subject: [PATCH] Fix: largestPrimeFactor function, Add: largestPrimeFactor(8)
 test (#38756)

* Fix `largestPrimeFactor(8)` result
* Improve `largestPrimeFactor` performance
* Add `largestPrimeFactor(8)` test
---
 .../problem-3-largest-prime-factor.english.md  | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-3-largest-prime-factor.english.md b/curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-3-largest-prime-factor.english.md
index 61eb2e3a4a..faf6be781d 100644
--- a/curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-3-largest-prime-factor.english.md
+++ b/curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-3-largest-prime-factor.english.md
@@ -34,6 +34,8 @@ tests:
     testString: assert.strictEqual(largestPrimeFactor(5), 5);
   - text: <code>largestPrimeFactor(7)</code> should return 7.
     testString: assert.strictEqual(largestPrimeFactor(7), 7);
+  - text: <code>largestPrimeFactor(8)</code> should return 2.
+    testString: assert.strictEqual(largestPrimeFactor(8), 2);
   - text: <code>largestPrimeFactor(13195)</code> should return 29.
     testString: assert.strictEqual(largestPrimeFactor(13195), 29);
   - text: <code>largestPrimeFactor(600851475143)</code> should return 6857.
@@ -68,14 +70,18 @@ largestPrimeFactor(13195);
 
 
 ```js
-const largestPrimeFactor = (number)=>{
+const largestPrimeFactor = (number) => {
   let largestFactor = number;
-  for(let i = 2;i<largestFactor;i++){
-  if(!(largestFactor%i)){
-    largestFactor = largestFactor/i;
-    largestPrimeFactor(largestFactor);
-  }
+
+  for (let i = 2; i <= Math.sqrt(largestFactor); i++) {
+    if (!(largestFactor % i)) {
+      let factor = largestFactor / i;
+      let candidate = largestPrimeFactor(factor);
+
+      return i > candidate ? i : candidate;
+    }
   }
+
   return largestFactor;
 }
 ```