feat(book:array): add solutions for interview questions

Author: amejiarosario

.vscode/settings.json

@@ -1,17 +1,3 @@
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book/D-interview-questions-solutions.asc

@@ -0,0 +1,31 @@
+[appendix]
+[[d-interview-questions-solutions]]
+== Interview Questions Solutions
+(((Interview Questions Solutions)))
+
+=== Solutions for Array Questions
+(((Interview Questions Solutions, Arrays)))
+
+==== Rotate Left
+include::content/part02/array.asc[tag=array-q-rotate-left]
+
+We are asked to rotate an array multiple times (`k`).
+
+One brute force solution, would be removing the first element and appending it to the end `k` times:
+
+include::interview-questions/rotate-array-left.js[tag=bruteForce]
+
+However, what would happen if the array is huge (millions of elements)?
+How efficient will be if `k` number is large (thousands)?
+
+When k is bigger than the array, it will loop back over and over again. We can avoid extra computation by calculating the final place using modulus.
+
+Here's the final solution:
+
+include::interview-questions/rotate-array-left.js[tag=description]
+include::interview-questions/rotate-array-left.js[tag=solution]
+
+It runs on `O(n^2)` while the brute force solution was doing `O(n^2 * k)`.
+
+==== Sum
+include::content/part02/array.asc[tag=array-sum]

book/ch02-git-basics-chapter.asc

@@ -17,7 +17,8 @@ TIP: Strings are a collection of Unicode characters and most of the array concep
 
 .Fixed vs. Dynamic Size Arrays
 ****
-Some programming languages have fixed size arrays like Java and C++. Fixed size arrays might be a hassle when your collection gets full, and you have to create a new one with a bigger size. For that, those programming languages also have built-in dynamic arrays: we have `vector` in C++ and `ArrayList` in Java. Dynamic programming languages like JavaScript, Ruby, and Python use dynamic arrays by default.
+Some programming languages have fixed size arrays like Java and C++.
+Fixed size arrays might be a hassle when your collection gets full, and you have to create a new one with a bigger size. For that, those programming languages also have built-in dynamic arrays: we have `vector` in C++ and `ArrayList` in Java. Dynamic programming languages like JavaScript, Ruby, and Python use dynamic arrays by default.
 ****
 
 Arrays look like this:
@@ -275,30 +276,21 @@ To sum up, the time complexity of an array is:
 |===
 //end::table
 
-==== Array Exercises
+==== Interview Questions
+(((Interview Questions, Arrays)))
 
+// tag::array-q-rotate-left[]
 1) Implement an efficient algorithm that rotate an array `a` an `k` number of times.
 
 [source, javascript]
 ----
-/**
- * Rotate an array left by k number of times.
- *
- * @example
- *    rotateLeft([1,2,3], 1); // [2,3,1]
- *    rotateLeft([1,2,3,4,5], 4); // [5,1,2,3,4]
- *
- *    rotateLeft(Array(1e6).fill(1), 1e4); // <scale testing>
- *
- * @param a - The array
- * @param k - The number of times the array is rotated
- */
-function rotateLeft(a, k) {
-  // write you code and test with examples
+include::../../interview-questions/rotate-array-left.js[tag=description]
+  // write you code here
 }
 ----
+// end::array-q-rotate-left[]
 
-
+// tag::array-sum[]
 2) Implement an algorithm that takes two arrays of numbers and return a new array with the sum.
 
 [source, javascript]
@@ -318,3 +310,4 @@ function sum(a, b) {
   // write you code and test with examples
 }
 ----
+// end::array-sum[]

book/content/part02/array.asc

@@ -82,4 +82,4 @@ Measurement is the first step that leads to control and eventually to improvemen
 
 Your feedback is very welcome and valuable. Let us know what your thoughts about this book — what you like or ideas to make it better.
 
-To send us feedback, e-mail us at [email protected], send a tweet to https://twitter.com/iAmAdrianMejia[@iAmAdrianMejia], or using the hash tags `#dsaJS`, `#javascript` and `#algorithms`.
+To send us feedback, e-mail us at [email protected], send a tweet to https://twitter.com/iAmAdrianMejia[@iAmAdrianMejia], or using the hash tag `#dsaJS`.

book/content/preface.asc

@@ -0,0 +1,34 @@
+// tag::description[]
+/**
+ * Rotate an array left by k number of times.
+ *
+ * @example
+ *    rotateLeft([1,2,3], 1); // [2,3,1]
+ *    rotateLeft([1,2,3,4,5], 4); // [5,1,2,3,4]
+ *
+ *    rotateLeft(Array(1e6).fill(1), 1e4); // <scale testing>
+ *
+ * @param a - The array
+ * @param k - The number of times the array is rotated
+ */
+function rotateLeft(a, k) {
+// end::description[]
+// tag::solution[]
+  const moves = k % a.length;
+  for (let i = 0; i < moves; i++) {
+    a.push(a.shift());
+  }
+  return a;
+}
+// end::solution[]
+
+// tag::bruteForce[]
+function rotateLeftBruteForce(a, k) {
+  for (let i = 0; i < k; i++) {
+    a.push(a.shift());
+  }
+  return a;
+}
+// end::bruteForce[]
+
+module.exports = { rotateLeft, rotateLeftBruteForce };

book/interview-questions/rotate-array-left.js

@@ -0,0 +1,19 @@
+const { rotateLeft, rotateLeftBruteForce } = require('./rotate-array-left');
+
+describe('Rotate Left', () => {
+  describe('when data is small', () => {
+    it('should work with 1', () => {
+      expect(rotateLeft([1, 2, 3], 1)).toEqual([2, 3, 1]);
+    });
+
+    it('should work with 4', () => {
+      expect(rotateLeft([1, 2, 3, 4, 5], 4)).toEqual([5, 1, 2, 3, 4]);
+    });
+  });
+
+  describe('when data is large', () => {
+    it('', () => {
+
+    });
+  });
+});

book/interview-questions/rotate-array-left.spec.js

@@ -117,3 +117,7 @@ alert('foo');
 console.log('bar');
 /* eslint-enable no-alert */
 ```
+
+# Asciidoctor Manual
+
+https://asciidoctor.org/docs/user-manual/