Feat: add new Markdown parser (#39800)

and change all the challenges to new `md` format.

curriculum/challenges/english/10-coding-interview-prep/rosetta-code/gray-code.md

@@ -1,72 +1,101 @@
 ---
-title: Gray code
 id: 5a23c84252665b21eecc7e80
+title: Gray code
 challengeType: 5
 forumTopicId: 302276
 ---
 
-## Description
-<section id='description'>
-<a href="https://en.wikipedia.org/wiki/Gray code" target="_blank">Gray code</a> is a form of binary encoding where transitions between consecutive numbers differ by only one bit.
-This is a useful encoding for reducing hardware data hazards with values that change rapidly and/or connect to slower hardware as inputs.
-It is also useful for generating inputs for <a href="https://en.wikipedia.org/wiki/Karnaugh map" target="_blank">Karnaugh maps</a> in order from left to right or top to bottom.
-</section>
+# --description--
+
+[Gray code](<https://en.wikipedia.org/wiki/Gray code>) is a form of binary encoding where transitions between consecutive numbers differ by only one bit.
+
+This is a useful encoding for reducing hardware data hazards with values that change rapidly and/or connect to slower hardware as inputs.
+
+It is also useful for generating inputs for [Karnaugh maps](<https://en.wikipedia.org/wiki/Karnaugh map>) in order from left to right or top to bottom.
+
+# --instructions--
 
-## Instructions
-<section id='instructions'>
 Create a function to encode a number to and decode a number from Gray code. The function should will have 2 parameters.
+
 The first would be a boolean. The function should encode for true and decode for false. The second parameter would be the number to be encoded/decoded.
+
 Display the normal binary representations, Gray code representations, and decoded Gray code values for all 5-bit binary numbers (0-31 inclusive, leading 0's not necessary).
+
 There are many possible Gray codes. The following encodes what is called "binary reflected Gray code."
+
 Encoding (MSB is bit 0, b is binary, g is Gray code):
-<pre>
-if b[i-1] = 1
+
+<pre>if b[i-1] = 1
   g[i] = not b[i]
 else
   g[i] = b[i]
 </pre>
+
 Or:
-<pre>
-g = b xor (b logically right shifted 1 time)
+
+<pre>g = b xor (b logically right shifted 1 time)
 </pre>
+
 Decoding (MSB is bit 0, b is binary, g is Gray code):
-<pre>
-b[0] = g[0]<br>
+
+<pre>b[0] = g[0]<br>
 for other bits:
 b[i] = g[i] xor b[i-1]
 </pre>
-</section>
 
-## Tests
-<section id='tests'>
+# --hints--
 
-```yml
-tests:
-  - text: <code>gray</code> should be a function.
-    testString: assert(typeof gray=='function');
-  - text: <code>gray(true,177)</code> should return a number.
-    testString: assert(typeof gray(true,177)=='number');
-  - text: <code>gray(true,177)</code> should return <code>233</code>.
-    testString: assert.equal(gray(true,177),233);
-  - text: <code>gray(true,425)</code> should return <code>381</code>.
-    testString: assert.equal(gray(true,425),381);
-  - text: <code>gray(true,870)</code> should return <code>725</code>.
-    testString: assert.equal(gray(true,870),725);
-  - text: <code>gray(false,233)</code> should return <code>177</code>.
-    testString: assert.equal(gray(false,233),177);
-  - text: <code>gray(false,381)</code> should return <code>425</code>.
-    testString: assert.equal(gray(false,381),425);
-  - text: <code>gray(false,725)</code> should return <code>870</code>.
-    testString: assert.equal(gray(false,725),870);
+`gray` should be a function.
 
+```js
+assert(typeof gray == 'function');
 ```
 
-</section>
+`gray(true,177)` should return a number.
 
-## Challenge Seed
-<section id='challengeSeed'>
+```js
+assert(typeof gray(true, 177) == 'number');
+```
 
-<div id='js-seed'>
+`gray(true,177)` should return `233`.
+
+```js
+assert.equal(gray(true, 177), 233);
+```
+
+`gray(true,425)` should return `381`.
+
+```js
+assert.equal(gray(true, 425), 381);
+```
+
+`gray(true,870)` should return `725`.
+
+```js
+assert.equal(gray(true, 870), 725);
+```
+
+`gray(false,233)` should return `177`.
+
+```js
+assert.equal(gray(false, 233), 177);
+```
+
+`gray(false,381)` should return `425`.
+
+```js
+assert.equal(gray(false, 381), 425);
+```
+
+`gray(false,725)` should return `870`.
+
+```js
+assert.equal(gray(false, 725), 870);
+```
+
+# --seed--
+
+## --seed-contents--
 
 ```js
 function gray(enc, number) {
@@ -74,15 +103,7 @@ function gray(enc, number) {
 }
 ```
 
-</div>
-
-
-
-</section>
-
-## Solution
-<section id='solution'>
-
+# --solutions--
 
 ```js
 function gray(enc, number){
@@ -97,7 +118,4 @@ function gray(enc, number){
       return n;
   }
 }
-
 ```
-
-</section>