add satellite

config.json

@@ -1173,6 +1173,14 @@
           "recursion"
         ]
       },
+      {
+        "slug": "satellite",
+        "name": "Satellite",
+        "uuid": "da0fa224-6095-4382-b869-f4e3953e09f6",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "sublist",
         "name": "Sublist",

exercises/practice/satellite/.docs/instructions.md

@@ -0,0 +1,27 @@
+# Instructions
+
+Imagine you need to transmit a binary tree to a satellite approaching Alpha Centauri and you have limited bandwidth.
+Since the tree has no repeating items it can be uniquely represented by its [pre-order and in-order traversals][wiki].
+
+Write the software for the satellite to rebuild the tree from the traversals.
+
+A pre-order traversal reads the value of the current node before (hence "pre") reading the left subtree in pre-order.
+Afterwards the right subtree is read in pre-order.
+
+An in-order traversal reads the left subtree in-order then the current node and finally the right subtree in-order.
+So in order from left to right.
+
+For example the pre-order traversal of this tree is [a, i, x, f, r].
+The in-order traversal of this tree is [i, a, f, x, r]
+
+```text
+  a
+ / \
+i   x
+   / \
+  f   r
+```
+
+Note: the first item in the pre-order traversal is always the root.
+
+[wiki]: https://en.wikipedia.org/wiki/Tree_traversal

exercises/practice/satellite/.meta/config.json

@@ -0,0 +1,25 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "satellite.ts"
+    ],
+    "test": [
+      "satellite.test.ts"
+    ],
+    "example": [
+      ".meta/proof.ci.ts"
+    ]
+  },
+  "custom": {
+    "version.tests.compatibility": "jest-29",
+    "flag.tests.task-per-describe": false,
+    "flag.tests.may-run-long": false,
+    "flag.tests.includes-optional": false,
+    "flag.tests.jest": true,
+    "flag.tests.tstyche": false
+  },
+  "blurb": "Rebuild binary trees from pre-order and in-order traversals."
+}

exercises/practice/satellite/.meta/proof.ci.ts

@@ -0,0 +1,56 @@
+export type Tree = {
+  v?: string
+  l?: Tree
+  r?: Tree
+}
+
+const hasUniqueItems = (items: string[]): boolean =>
+  new Set(items).size === items.length
+
+const hasSameItems = (left: string[], right: string[]): boolean => {
+  const rightItems = new Set(right)
+  return left.every((item) => rightItems.has(item))
+}
+
+const validateTraversals = (preorder: string[], inorder: string[]): void => {
+  if (preorder.length !== inorder.length) {
+    throw new Error('traversals must have the same length')
+  }
+
+  if (!hasUniqueItems(preorder) || !hasUniqueItems(inorder)) {
+    throw new Error('traversals must contain unique items')
+  }
+
+  if (!hasSameItems(preorder, inorder)) {
+    throw new Error('traversals must have the same elements')
+  }
+}
+
+const buildTree = (preorder: string[], inorder: string[]): Tree => {
+  if (preorder.length === 0) {
+    return {}
+  }
+
+  const [root, ...remainingPreorder] = preorder
+  const rootIndex = inorder.indexOf(root)
+  const leftInorder = inorder.slice(0, rootIndex)
+  const rightInorder = inorder.slice(rootIndex + 1)
+  const leftSize = leftInorder.length
+  const leftPreorder = remainingPreorder.slice(0, leftSize)
+  const rightPreorder = remainingPreorder.slice(leftSize)
+
+  return {
+    v: root,
+    l: buildTree(leftPreorder, leftInorder),
+    r: buildTree(rightPreorder, rightInorder),
+  }
+}
+
+export const treeFromTraversals = (
+  preorder: string[],
+  inorder: string[]
+): Tree => {
+  validateTraversals(preorder, inorder)
+
+  return buildTree(preorder, inorder)
+}

exercises/practice/satellite/.meta/tests.toml

@@ -0,0 +1,37 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[8df3fa26-811a-4165-9286-ff9ac0850d19]
+description = "Empty tree"
+
+[f945ccfc-05e3-47d7-825b-0270559d43ad]
+description = "Tree with one item"
+
+[a0121d5f-37b0-48dd-9c64-cba4c4464135]
+description = "Tree with many items"
+
+[6074041f-4891-4d81-a128-401050c2a3b0]
+description = "Reject traversals of different length"
+
+[27916ce4-45f3-4d8b-8528-496fedc157ca]
+description = "Reject inconsistent traversals of same length"
+
+[d86a3d72-76a9-43b5-9d3a-e64cb1216035]
+description = "Reject traversals with repeated items"
+
+[af31ae02-7e5b-4452-a990-bccb3fca9148]
+description = "A degenerate binary tree"
+
+[ee54463d-a719-4aae-ade4-190d30ce7320]
+description = "Another degenerate binary tree"
+
+[87123c08-c155-4486-90a4-e2f75b0f3e8f]
+description = "Tree with many more items"

exercises/practice/satellite/.vscode/extensions.json

@@ -0,0 +1,7 @@
+{
+  "recommendations": [
+    "arcanis.vscode-zipfs",
+    "dbaeumer.vscode-eslint",
+    "esbenp.prettier-vscode"
+  ]
+}

exercises/practice/satellite/.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+  "cSpell.words": ["exercism"],
+  "search.exclude": {
+    "**/.yarn": true,
+    "**/.pnp.*": true
+  }
+}

exercises/practice/satellite/.yarnrc.yml

@@ -0,0 +1,3 @@
+compressionLevel: mixed
+
+enableGlobalCache: true

exercises/practice/satellite/babel.config.cjs

@@ -0,0 +1,5 @@
+module.exports = {
+  // eslint-disable-next-line @typescript-eslint/no-require-imports
+  presets: [[require('@exercism/babel-preset-typescript'), { corejs: '3.38' }]],
+  plugins: [],
+}

exercises/practice/satellite/eslint.config.mjs

@@ -0,0 +1,26 @@
+// @ts-check
+
+import tsEslint from 'typescript-eslint'
+import config from '@exercism/eslint-config-typescript'
+import maintainersConfig from '@exercism/eslint-config-typescript/maintainers.mjs'
+
+export default [
+  ...tsEslint.config(...config, {
+    files: ['.meta/proof.ci.ts', '.meta/exemplar.ts', '*.test.ts'],
+    extends: maintainersConfig,
+  }),
+  {
+    ignores: [
+      // # Protected or generated
+      '.git/**/*',
+      '.vscode/**/*',
+
+      //# When using npm
+      'node_modules/**/*',
+
+      // # Configuration files
+      'babel.config.cjs',
+      'jest.config.cjs',
+    ],
+  },
+]

exercises/practice/satellite/jest.config.cjs

@@ -0,0 +1,22 @@
+module.exports = {
+  verbose: true,
+  projects: ['<rootDir>'],
+  testMatch: [
+    '**/__tests__/**/*.[jt]s?(x)',
+    '**/test/**/*.[jt]s?(x)',
+    '**/?(*.)+(spec|test).[jt]s?(x)',
+  ],
+  testPathIgnorePatterns: [
+    '/(?:production_)?node_modules/',
+    '.d.ts$',
+    '<rootDir>/test/fixtures',
+    '<rootDir>/test/helpers',
+    '__mocks__',
+  ],
+  transform: {
+    '^.+\\.[jt]sx?$': 'babel-jest',
+  },
+  moduleNameMapper: {
+    '^(\\.\\/.+)\\.js$': '$1',
+  },
+}

exercises/practice/satellite/package.json

@@ -0,0 +1,38 @@
+{
+  "name": "@exercism/typescript-satellite",
+  "version": "1.0.0",
+  "description": "Exercism exercises in Typescript.",
+  "private": true,
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/exercism/typescript"
+  },
+  "type": "module",
+  "engines": {
+    "node": "^18.16.0 || >=20.0.0"
+  },
+  "devDependencies": {
+    "@exercism/babel-preset-typescript": "^0.6.0",
+    "@exercism/eslint-config-typescript": "^0.8.0",
+    "@jest/globals": "^29.7.0",
+    "@types/node": "~22.7.6",
+    "babel-jest": "^29.7.0",
+    "core-js": "~3.38.1",
+    "eslint": "^9.12.0",
+    "expect": "^29.7.0",
+    "jest": "^29.7.0",
+    "prettier": "^3.3.3",
+    "tstyche": "^2.1.1",
+    "typescript": "~5.6.3",
+    "typescript-eslint": "^8.10.0"
+  },
+  "scripts": {
+    "test": "corepack yarn node test-runner.mjs",
+    "test:types": "corepack yarn tstyche",
+    "test:implementation": "corepack yarn jest --no-cache --passWithNoTests",
+    "lint": "corepack yarn lint:types && corepack yarn lint:ci",
+    "lint:types": "corepack yarn tsc --noEmit -p .",
+    "lint:ci": "corepack yarn eslint . --ext .tsx,.ts"
+  },
+  "packageManager": "yarn@4.5.1"
+}