Add binary-search-tree (#386)

Author: BNAndras

config.json

@@ -654,6 +654,14 @@
           "strings"
         ]
       },
+      {
+        "slug": "binary-search-tree",
+        "name": "Binary Search Tree",
+        "uuid": "4e8df8d7-2ca6-4c2b-9e0f-1f6a05ac8c57",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "camicia",
         "name": "Camicia",

exercises/practice/binary-search-tree/.docs/instructions.md

@@ -0,0 +1,70 @@
+# Instructions
+
+Insert and search for numbers in a binary tree.
+
+When we need to represent sorted data, an array does not make a good data structure.
+
+Say we have the array `[1, 3, 4, 5]`, and we add 2 to it so it becomes `[1, 3, 4, 5, 2]`.
+Now we must sort the entire array again!
+We can improve on this by realizing that we only need to make space for the new item `[1, nil, 3, 4, 5]`, and then adding the item in the space we added.
+But this still requires us to shift many elements down by one.
+
+Binary Search Trees, however, can operate on sorted data much more efficiently.
+
+A binary search tree consists of a series of connected nodes.
+Each node contains a piece of data (e.g. the number 3), a variable named `left`, and a variable named `right`.
+The `left` and `right` variables point at `nil`, or other nodes.
+Since these other nodes in turn have other nodes beneath them, we say that the left and right variables are pointing at subtrees.
+All data in the left subtree is less than or equal to the current node's data, and all data in the right subtree is greater than the current node's data.
+
+For example, if we had a node containing the data 4, and we added the data 2, our tree would look like this:
+
+![A graph with root node 4 and a single child node 2.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2.svg)
+
+```text
+      4
+     /
+    2
+```
+
+If we then added 6, it would look like this:
+
+![A graph with root node 4 and two child nodes 2 and 6.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2-6.svg)
+
+```text
+      4
+     / \
+    2   6
+```
+
+If we then added 3, it would look like this
+
+![A graph with root node 4, two child nodes 2 and 6, and a grandchild node 3.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2-6-3.svg)
+
+```text
+       4
+     /   \
+    2     6
+     \
+      3
+```
+
+And if we then added 1, 5, and 7, it would look like this
+
+![A graph with root node 4, two child nodes 2 and 6, and four grandchild nodes 1, 3, 5 and 7.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2-6-1-3-5-7.svg)
+
+```text
+          4
+        /   \
+       /     \
+      2       6
+     / \     / \
+    1   3   5   7
+```
+
+## Credit
+
+The images were created by [habere-et-dispertire][habere-et-dispertire] using [PGF/TikZ][pgf-tikz] by Till Tantau.
+
+[habere-et-dispertire]: https://exercism.org/profiles/habere-et-dispertire
+[pgf-tikz]: https://en.wikipedia.org/wiki/PGF/TikZ

exercises/practice/binary-search-tree/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "binary_search_tree.vim"
+    ],
+    "test": [
+      "binary_search_tree.vader"
+    ],
+    "example": [
+      ".meta/example.vim"
+    ]
+  },
+  "blurb": "Insert and search for numbers in a binary tree.",
+  "source": "Josh Cheek"
+}

exercises/practice/binary-search-tree/.meta/example.vim

@@ -0,0 +1,42 @@
+function! Data(treeData) abort
+  if empty(a:treeData)
+    return v:null
+  endif
+
+  let l:tree = s:Node(a:treeData[0])
+  for l:value in a:treeData[1:]
+    let l:tree = s:Insert(l:tree, l:value)
+  endfor
+
+  return l:tree
+endfunction
+
+function! SortedData(treeData) abort
+  return s:InOrder(Data(a:treeData))
+endfunction
+
+function! s:Insert(tree, value) abort
+  if a:tree is v:null
+    return s:Node(a:value)
+  endif
+
+  if a:value <=# a:tree.data
+    let a:tree.left = s:Insert(a:tree.left, a:value)
+  else
+    let a:tree.right = s:Insert(a:tree.right, a:value)
+  endif
+
+  return a:tree
+endfunction
+
+function! s:Node(value) abort
+  return {'data': a:value, 'left': v:null, 'right': v:null}
+endfunction
+
+function! s:InOrder(tree) abort
+  if a:tree is v:null
+    return []
+  endif
+
+  return s:InOrder(a:tree.left) + [a:tree.data] + s:InOrder(a:tree.right)
+endfunction

exercises/practice/binary-search-tree/.meta/tests.toml

@@ -0,0 +1,40 @@
+# 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.
+
+[e9c93a78-c536-4750-a336-94583d23fafa]
+description = "data is retained"
+
+[7a95c9e8-69f6-476a-b0c4-4170cb3f7c91]
+description = "smaller number at left node"
+
+[22b89499-9805-4703-a159-1a6e434c1585]
+description = "same number at left node"
+
+[2e85fdde-77b1-41ed-b6ac-26ce6b663e34]
+description = "greater number at right node"
+
+[dd898658-40ab-41d0-965e-7f145bf66e0b]
+description = "can create complex tree"
+
+[9e0c06ef-aeca-4202-b8e4-97f1ed057d56]
+description = "can sort single number"
+
+[425e6d07-fceb-4681-a4f4-e46920e380bb]
+description = "can sort if second number is smaller than first"
+
+[bd7532cc-6988-4259-bac8-1d50140079ab]
+description = "can sort if second number is same as first"
+
+[b6d1b3a5-9d79-44fd-9013-c83ca92ddd36]
+description = "can sort if second number is greater than first"
+
+[d00ec9bd-1288-4171-b968-d44d0808c1c8]
+description = "can sort complex tree"

exercises/practice/binary-search-tree/binary_search_tree.vader

@@ -0,0 +1,101 @@
+Execute (data is retained):
+  let g:treeData = ['4']
+  let g:expected = {'data': '4', 'left': v:null, 'right': v:null}
+  AssertEqual g:expected, Data(g:treeData)
+
+Execute (smaller number at left node):
+  let g:treeData = ['4', '2']
+  let g:expected = {
+  \   'data': '4',
+  \   'left': {
+  \     'data': '2',
+  \     'left': v:null,
+  \     'right': v:null
+  \   },
+  \   'right': v:null
+  \ }
+  AssertEqual g:expected, Data(g:treeData)
+
+Execute (same number at left node):
+  let g:treeData = ['4', '4']
+  let g:expected = {
+  \   'data': '4',
+  \   'left': {
+  \     'data': '4',
+  \     'left': v:null,
+  \     'right': v:null
+  \   },
+  \   'right': v:null
+  \ }
+  AssertEqual g:expected, Data(g:treeData)
+
+Execute (greater number at right node):
+  let g:treeData = ['4', '5']
+  let g:expected = {
+  \   'data': '4',
+  \   'left': v:null,
+  \   'right': {
+  \     'data': '5',
+  \     'left': v:null,
+  \     'right': v:null
+  \   }
+  \ }
+  AssertEqual g:expected, Data(g:treeData)
+
+Execute (can create complex tree):
+  let g:treeData = ['4', '2', '6', '1', '3', '5', '7']
+  let g:expected = {
+  \   'data': '4',
+  \   'left': {
+  \     'data': '2',
+  \     'left': {
+  \       'data': '1',
+  \       'left': v:null,
+  \       'right': v:null
+  \     },
+  \     'right': {
+  \       'data': '3',
+  \       'left': v:null,
+  \       'right': v:null
+  \     }
+  \   },
+  \   'right': {
+  \     'data': '6',
+  \     'left': {
+  \       'data': '5',
+  \       'left': v:null,
+  \       'right': v:null
+  \     },
+  \     'right': {
+  \       'data': '7',
+  \       'left': v:null,
+  \       'right': v:null
+  \     }
+  \   }
+  \ }
+  AssertEqual g:expected, Data(g:treeData)
+
+Execute (can sort single number):
+  let g:treeData = ['2']
+  let g:expected = ['2']
+  AssertEqual g:expected, SortedData(g:treeData)
+
+Execute (can sort if second number is smaller than first):
+  let g:treeData = ['2', '1']
+  let g:expected = ['1', '2']
+  AssertEqual g:expected, SortedData(g:treeData)
+
+Execute (can sort if second number is same as first):
+  let g:treeData = ['2', '2']
+  let g:expected = ['2', '2']
+  AssertEqual g:expected, SortedData(g:treeData)
+
+Execute (can sort if second number is greater than first):
+  let g:treeData = ['2', '3']
+  let g:expected = ['2', '3']
+  AssertEqual g:expected, SortedData(g:treeData)
+
+Execute (can sort complex tree):
+  let g:treeData = ['2', '1', '3', '6', '7', '5']
+  let g:expected = ['1', '2', '3', '5', '6', '7']
+  AssertEqual g:expected, SortedData(g:treeData)

exercises/practice/binary-search-tree/binary_search_tree.vim

@@ -0,0 +1,11 @@
+"
+" Insert a sequence of values into a binary search tree and return the tree
+" or its data in sorted order.
+"
+function! Data(treeData) abort
+  " your solution goes here
+endfunction
+
+function! SortedData(treeData) abort
+  " your solution goes here
+endfunction

lib/generate.vim

@@ -113,8 +113,59 @@ function! s:filter_test_cases(cases, excluded_uuids) abort
   return filtered
 endfunction
 
-function! s:generate_variable(name, value)
-  call append(line('$'), printf('  let g:%s = %s', a:name, string(a:value)))
+function! s:dict_literal(dict) abort
+  if empty(a:dict)
+    return ['{}']
+  endif
+
+  let lines = ['{']
+  let key_names = sort(keys(a:dict))
+  let last_key = key_names[-1]
+
+  for key_name in key_names
+    let key_fragment = string(key_name) . ': '
+    let value = a:dict[key_name]
+
+    if type(value) ==# type({})
+      let entry_lines = s:dict_literal(value)
+      let entry_lines[0] = key_fragment . entry_lines[0]
+    else
+      let entry_lines = [key_fragment . string(value)]
+    endif
+
+    let entry_lines = s:indent_lines(entry_lines)
+    if key_name !=# last_key
+      let entry_lines[-1] .= ','
+    endif
+    call extend(lines, entry_lines)
+  endfor
+
+  call add(lines, '}')
+  return lines
+endfunction
+
+function! s:indent_lines(lines) abort
+  let indented = []
+  for line in a:lines
+    call add(indented, '  ' . line)
+  endfor
+  return indented
+endfunction
+
+function! s:generate_variable(name, value) abort
+  let binding = printf('  let g:%s = ', a:name)
+  let inline = binding . string(a:value)
+
+  if strdisplaywidth(inline) <= 80 || type(a:value) !=# type({})
+    call append(line('$'), inline)
+    return
+  endif
+
+  let value_lines = s:dict_literal(a:value)
+  call append(line('$'), binding . value_lines[0])
+  for line in value_lines[1:]
+    call append(line('$'), '  \ ' . line)
+  endfor
 endfunction
 
 function! s:generate_assert(test, arguments) abort