Curriculum change: track sequence (round 1) (#590)

* Reorder exercises according to Round 1

As part of the ongoing curriculum update, this re-orders the core exercises according to perceived difficulty. Most notably, this moves simple-cipher down -- re-orders the list loosly according to this:

hello-world, gigasecond, leap, rna-transcription, bob, pangram, space-age, matrix, linked-list, grade-school, robot-name, pascals-triangle, simple-cipher, wordy, secret-handshake, list-ops

Since it's a bit weird to introduce Date thát early, it's placed after leap --- for now.

Furthermore this moves all the core exercises to the top and all the side exercises unlocked by these below that, in order. The bonus exercises (always unlocked) are at the bottom.

* Demote prime-factors from core to side exercise

Prime factors is a mathy exercise and as part of round one, mathy exercises should be demoted to side exercise.

* Update simple-cipher difficulty

This is an extensive exercise with four parts. Even though it's not a particularly difficult one to understand, it's actually difficult for beginners (< 4) to implement. Making this number higher makes sure it's no longer listed as easy.

* Add helper binaries for printing the tree of exercises

* Fix the script to include core exercises that don't unlock anything

* nit: junction for the last item in the list

* Re-assign prime-factors unlocks

Assigning them one up, and give two exercises to "secret-handshake" which had none.

* Reorder based on mentor-notes, examples and conversation

- Moving bob down
- Moving list-ops up
- Moving space-age up (because of new exercise implementation)

* Remove .gitattributes

* Tweak difficulties

* Update config.json orderering to match track:

Core (matches config.json) of this track:
- hello-world (1)
- leap (1)
- gigasecond (1)
- rna-transcription (2)
- space-age (2)
- pangram (2)
- matrix (3)
- bob (4)
- pascals-triangle (4)
- linked-list (5)
- grade-school (5)
- list-ops (6)
- robot-name (6)
- simple-cipher (6)
- wordy (7)
- secret-handshake (6)


core
----
├─ hello-world
│  └─ two-fer (1)
│
├─ leap
│  ├─ reverse-string (2)
│  ├─ triangle (3)
│  └─ collatz-conjecture (3)
│
├─ gigasecond
│  ├─ clock (5)
│  └─ meetup (7)
│
├─ rna-transcription
│  ├─ hamming (2)
│  ├─ etl (2)
│  ├─ scrabble-score (5)
│  ├─ raindrops (2)
│  ├─ allergies (6)
│  └─ nucleotide-count (4)
│
├─ space-age
│  ├─ word-count (1)
│  ├─ grains (5)
│  ├─ perfect-numbers (3)
│  ├─ luhn (4)
│  ├─ pythagorean-triplet (5)
│  ├─ difference-of-squares (3)
│  ├─ complex-numbers (4)
│  ├─ prime-factors (4)
│  └─ palindrome-products (7)
│
├─ pangram
│  ├─ isogram (2)
│  ├─ phone-number (3)
│  ├─ anagram (1)
│  ├─ acronym (2)
│  ├─ series (3)
│  ├─ largest-series-product (7)
│  ├─ bracket-push (3)
│  └─ high-scores (2)
│
├─ matrix
│  ├─ forth (8)
│  ├─ saddle-points (6)
│  ├─ ocr-numbers (5)
│  ├─ transpose (1)
│  ├─ spiral-matrix (4)
│  └─ rectangles (4)
│
├─ bob
│  ├─ beer-song (5)
│  ├─ food-chain (4)
│  ├─ pig-latin (4)
│  ├─ proverb (4)
│  ├─ house (4)
│  ├─ twelve-days (4)
│  ├─ say (6)
│  └─ isbn-verifier (4)
│
├─ pascals-triangle
│  ├─ diamond (5)
│  └─ rational-numbers (5)
│
├─ linked-list
│  ├─ sublist (4)
│  ├─ word-search (8)
│  ├─ circular-buffer (8)
│  ├─ binary-search (7)
│  ├─ binary-search-tree (6)
│  ├─ custom-set (6)
│  └─ simple-linked-list (8)
│
├─ grade-school
│  ├─ two-bucket (6)
│  ├─ bowling (8)
│  ├─ alphametics (7)
│  ├─ connect (7)
│  └─ variable-length-quantity (5)
│
├─ list-ops
│  ├─ strain (4)
│  ├─ accumulate (5)
│  └─ flatten-array (5)
│
├─ robot-name
│  ├─ sieve (5)
│  └─ nth-prime (5)
│
├─ simple-cipher
│  ├─ atbash-cipher (7)
│  ├─ crypto-square (9)
│  ├─ diffie-hellman (3)
│  └─ rotational-cipher (2)
│
├─ wordy
│  ├─ kindergarten-garden (7)
│  └─ robot-simulator (5)
│
├─ secret-handshake
│  ├─ sum-of-multiples (5)
│  └─ change (8)

bonus
----
- zipper (8)
- darts (3)
- run-length-encoding (2)
- roman-numerals (3)
- react (8)
- queen-attack (8)
- all-your-base (5)
- minesweeper (7)
- protein-translation (1)
- armstrong-numbers (2)
- trinary (4)
- octal (4)
- hexadecimal (4)
- point-mutations (0)
- binary (4)

bin/generate-config-tree

@@ -0,0 +1,35 @@
+#!/usr/bin/env node
+
+const { exercises } = require('../config.json')
+const TAG_CORE = '__core'
+const TAG_BONUS = '__bonus'
+
+// node inter-opt exports
+exports.TAG_CORE = TAG_CORE
+exports.TAG_BONUS = TAG_BONUS
+
+exports.tree = exercises.reduce((result, exercise) => {
+    const tag = exercise.slug
+    const item = {
+        slug: tag,
+        difficulty: exercise.difficulty,
+    }
+
+    if (exercise.core) {
+        const current = result[TAG_CORE] || []
+
+        if (result[tag]) {
+            console.warn(`${tag} is not ordered correctly in config.json`)
+        }
+
+        return {
+            ...result,
+            __core: current.concat([item]),
+            [tag]: result[tag] || []
+        }
+    }
+
+    const parent = exercise.unlocked_by || TAG_BONUS
+    const current = result[parent] || []
+    return { ...result, [parent]: current.concat([item]) }
+}, {})

bin/print-config-tree

@@ -0,0 +1,34 @@
+#!/usr/bin/env node
+
+const actions = require('./generate-config-tree')
+
+const { tree, TAG_BONUS, TAG_CORE } = actions
+const { [TAG_BONUS]: __bonus, [TAG_CORE]: __core, ...track } = tree
+
+function printLn(line) {
+    process.stdout.write(`${line}\n`)
+}
+
+function printList(items) {
+    items.forEach(item => {
+        printLn(`- ${item.slug} (${item.difficulty})`)
+    })
+}
+
+printLn('Core (matches config.json) of this track:')
+printList(__core)
+printLn('\n')
+printLn('core')
+printLn('----')
+Object.keys(track).forEach(slug => {
+    printLn(`├─ ${slug}`)
+    track[slug].forEach((side, index, self) => {
+        junction = index === self.length - 1 ? '└─' : '├─'
+        printLn(`│  ${junction} ${side.slug} (${side.difficulty})`)
+    })
+    printLn('│')
+})
+
+printLn('bonus')
+printLn('----')
+printList(__bonus)