From dd4c7e0097f6f4cf2b6804b85a7c8de688d635f9 Mon Sep 17 00:00:00 2001
From: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>
Date: Wed, 20 Jan 2021 22:23:10 -0700
Subject: [PATCH] fix(learn): Update text as code for vector-dot-product
 (#40460)

* fix: implemented suggestted changes

* fix: correct last test expected return value

* fix: remove slash

Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>

* fix: remove slash

Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>

* fix: add test to return null if more than 2 vectors

Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>

* fix: added correct solution

* fix: removed extra brackets

Co-authored-by: Yuval Levental <yhl3051@rit.edu>

Co-authored-by: Lakshya Baghel <lakshyab.1999@gmail.com>
Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>
Co-authored-by: Yuval Levental <yhl3051@rit.edu>
---
 .../rosetta-code/vector-dot-product.md        | 50 +++++++------------
 1 file changed, 18 insertions(+), 32 deletions(-)

diff --git a/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/vector-dot-product.md b/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/vector-dot-product.md
index 962a9ac6c3..fb8ae242ae 100644
--- a/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/vector-dot-product.md
+++ b/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/vector-dot-product.md
@@ -8,57 +8,54 @@ dashedName: vector-dot-product
 
 # --description--
 
-A vector is defined as having three dimensions as being represented by an ordered collection of three numbers: (X, Y, Z).
+A vector can have one or more values represented by an ordered collection. Examples could be (x), (x, y), or (x, y, z).
 
 # --instructions--
 
-Write a function that takes any numbers of vectors (arrays) as input and computes their dot product. Your function should return `null` on invalid inputs such as vectors of different lengths.
+Write a function that takes two vectors (represented as one-dimensional arrays) as input and computes their dot product. Your function should return `null` on invalid inputs such as vectors of different lengths or passing anything other than two vectors.
 
 # --hints--
 
-dotProduct should be a function.
+`dotProduct` should be a function.
 
 ```js
 assert.equal(typeof dotProduct, 'function');
 ```
 
-dotProduct() should return null.
+`dotProduct()` should return `null`.
 
 ```js
 assert.equal(dotProduct(), null);
 ```
 
-dotProduct(\[[1], [1]]) should return 1.
+`dotProduct([1], [1])` should return `1`.
 
 ```js
 assert.equal(dotProduct([1], [1]), 1);
 ```
 
-dotProduct(\[[1], [1, 2]]) should return null.
+`dotProduct([1], [1, 2])` should return `null`.
 
 ```js
 assert.equal(dotProduct([1], [1, 2]), null);
 ```
 
-dotProduct([1, 3, -5], [4, -2, -1]) should return 3.
+`dotProduct([1, 3, -5], [4, -2, -1])` should return `3`.
 
 ```js
 assert.equal(dotProduct([1, 3, -5], [4, -2, -1]), 3);
 ```
 
-`dotProduct(...nVectors)` should return 156000.
+`dotProduct([3, 2, 1], [2, 4, 2], [5, 3, 1])` should return `null`.
 
 ```js
-assert.equal(
-  dotProduct(
-    [0, 1, 2, 3, 4],
-    [0, 2, 4, 6, 8],
-    [0, 3, 6, 9, 12],
-    [0, 4, 8, 12, 16],
-    [0, 5, 10, 15, 20]
-  ),
-  156000
-);
+assert.equal(dotProduct([3, 2, 1], [2, 4, 2], [5, 3, 1]), null);
+```
+
+`dotProduct([ 0, 3, 6, 9, 12 ], [ 0, 4, 8, 12, 16 ])` should return `360`.
+
+```js
+assert.equal(dotProduct([ 0, 3, 6, 9, 12 ], [ 0, 4, 8, 12, 16 ]), 360);
 ```
 
 # --seed--
@@ -75,29 +72,18 @@ function dotProduct(...vectors) {
 
 ```js
 function dotProduct(...vectors) {
-  if (!vectors || !vectors.length) {
-    return null;
-  }
-  if (!vectors[0] || !vectors[0].length) {
+  if (!vectors || !vectors.length || vectors.length > 2 || vectors[0].length !== vectors[1].length) {
     return null;
   }
   const vectorLen = vectors[0].length;
-  const numVectors = vectors.length;
-
-  // If all vectors not same length, return null
-  for (let i = 0; i < numVectors; i++) {
-    if (vectors[i].length !== vectorLen) {
-      return null;  // return undefined
-    }
-  }
 
   let prod = 0;
   let sum = 0;
   let j = vectorLen;
-  let i = numVectors;
+  let i = 2;
   // Sum terms
   while (j--) {
-    i = numVectors;
+    i = 2;
     prod = 1;
 
     while (i--) {