binary_search_tree

This commit is contained in:
Danil Negrienko 2024-07-01 13:56:40 -04:00
parent 1610d6caf3
commit e0d8231e91
10 changed files with 374 additions and 0 deletions

View File

@ -0,0 +1,25 @@
{
"authors": [
"sngeth"
],
"contributors": [
"angelikatyborska",
"Cohen-Carlisle",
"devonestes",
"neenjaw",
"sotojuan"
],
"files": {
"solution": [
"lib/binary_search_tree.ex"
],
"test": [
"test/binary_search_tree_test.exs"
],
"example": [
".meta/example.ex"
]
},
"blurb": "Insert and search for numbers in a binary tree.",
"source": "Josh Cheek"
}

View File

@ -0,0 +1 @@
{"track":"elixir","exercise":"binary-search-tree","id":"fc6ed3ee9f82408eb78d0f9df5e506bf","url":"https://exercism.org/tracks/elixir/exercises/binary-search-tree","handle":"negrienko","is_requester":true,"auto_approve":false}

View File

@ -0,0 +1,4 @@
# Used by "mix format"
[
inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
]

24
elixir/binary-search-tree/.gitignore vendored Normal file
View File

@ -0,0 +1,24 @@
# The directory Mix will write compiled artifacts to.
/_build/
# If you run "mix test --cover", coverage assets end up here.
/cover/
# The directory Mix downloads your dependencies sources to.
/deps/
# Where third-party dependencies like ExDoc output generated docs.
/doc/
# Ignore .fetch files in case you like to edit your project deps locally.
/.fetch
# If the VM crashes, it generates a dump, let's ignore it too.
erl_crash.dump
# Also ignore archive artifacts (built via "mix archive.build").
*.ez
# Ignore package tarball (built via "mix hex.build").
binary_search_tree-*.tar

View File

@ -0,0 +1,75 @@
# Help
## Running the tests
From the terminal, change to the base directory of the exercise then execute the tests with:
```bash
$ mix test
```
This will execute the test file found in the `test` subfolder -- a file ending in `_test.exs`
Documentation:
* [`mix test` - Elixir's test execution tool](https://hexdocs.pm/mix/Mix.Tasks.Test.html)
* [`ExUnit` - Elixir's unit test library](https://hexdocs.pm/ex_unit/ExUnit.html)
## Pending tests
In test suites of practice exercises, all but the first test have been tagged to be skipped.
Once you get a test passing, you can unskip the next one by commenting out the relevant `@tag :pending` with a `#` symbol.
For example:
```elixir
# @tag :pending
test "shouting" do
assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
end
```
If you wish to run all tests at once, you can include all skipped test by using the `--include` flag on the `mix test` command:
```bash
$ mix test --include pending
```
Or, you can enable all the tests by commenting out the `ExUnit.configure` line in the file `test/test_helper.exs`.
```elixir
# ExUnit.configure(exclude: :pending, trace: true)
```
## Useful `mix test` options
* `test/<FILE>.exs:LINENUM` - runs only a single test, the test from `<FILE>.exs` whose definition is on line `LINENUM`
* `--failed` - runs only tests that failed the last time they ran
* `--max-failures` - the suite stops evaluating tests when this number of test failures
is reached
* `--seed 0` - disables randomization so the tests in a single file will always be ran
in the same order they were defined in
## Submitting your solution
You can submit your solution using the `exercism submit lib/binary_search_tree.ex` command.
This command will upload your solution to the Exercism website and print the solution page's URL.
It's possible to submit an incomplete solution which allows you to:
- See how others have completed the exercise
- Request help from a mentor
## Need to get help?
If you'd like help solving the exercise, check the following pages:
- The [Elixir track's documentation](https://exercism.org/docs/tracks/elixir)
- The [Elixir track's programming category on the forum](https://forum.exercism.org/c/programming/elixir)
- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
If you're stuck on something, it may help to look at some of the [available resources](https://exercism.org/docs/tracks/elixir/resources) out there where answers might be found.

View File

@ -0,0 +1,70 @@
# Binary Search Tree
Welcome to Binary Search Tree on Exercism's Elixir Track.
If you need help running the tests or submitting your code, check out `HELP.md`.
## 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:
4
/
2
If we then added 6, it would look like this:
4
/ \
2 6
If we then added 3, it would look like this
4
/ \
2 6
\
3
And if we then added 1, 5, and 7, it would look like this
4
/ \
/ \
2 6
/ \ / \
1 3 5 7
## Source
### Created by
- @sngeth
### Contributed to by
- @angelikatyborska
- @Cohen-Carlisle
- @devonestes
- @neenjaw
- @sotojuan
### Based on
Josh Cheek

View File

@ -0,0 +1,26 @@
defmodule BinarySearchTree do
@type bst_node :: %{data: any, left: bst_node | nil, right: bst_node | nil}
@doc """
Create a new Binary Search Tree with root's value as the given 'data'
"""
@spec new(any) :: bst_node
def new(data), do: %{data: data, left: nil, right: nil}
@doc """
Creates and inserts a node with its value as 'data' into the tree.
"""
@spec insert(bst_node, any) :: bst_node
def insert(nil, data), do: new(data)
def insert(tree, data) when data <= tree.data, do:
%{tree | left: insert(tree.left, data)}
def insert(tree, data), do:
%{tree | right: insert(tree.right, data)}
@doc """
Traverses the Binary Search Tree in order and returns a list of each node's data.
"""
@spec in_order(bst_node) :: [any]
def in_order(nil), do: []
def in_order(tree), do: in_order(tree.left) ++ [tree.data | in_order(tree.right)]
end

View File

@ -0,0 +1,28 @@
defmodule BinarySearchTree.MixProject do
use Mix.Project
def project do
[
app: :binary_search_tree,
version: "0.1.0",
# elixir: "~> 1.8",
start_permanent: Mix.env() == :prod,
deps: deps()
]
end
# Run "mix help compile.app" to learn about applications.
def application do
[
extra_applications: [:logger]
]
end
# Run "mix help deps" to learn about dependencies.
defp deps do
[
# {:dep_from_hexpm, "~> 0.3.0"},
# {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
]
end
end

View File

@ -0,0 +1,119 @@
defmodule BinarySearchTreeTest do
use ExUnit.Case
test "data is retained" do
root = BinarySearchTree.new(4)
assert root.data == 4
assert root.left == nil
assert root.right == nil
end
describe "insert data at proper node" do
test "smaller number at left node" do
root =
BinarySearchTree.new(4)
|> BinarySearchTree.insert(2)
assert root.data == 4
assert root.left.data == 2
assert root.left.left == nil
assert root.left.right == nil
assert root.right == nil
end
test "same number at left node" do
root =
BinarySearchTree.new(4)
|> BinarySearchTree.insert(4)
assert root.data == 4
assert root.left.data == 4
assert root.left.left == nil
assert root.left.right == nil
assert root.right == nil
end
test "greater number at right node" do
root =
BinarySearchTree.new(4)
|> BinarySearchTree.insert(5)
assert root.data == 4
assert root.left == nil
assert root.right.data == 5
assert root.right.left == nil
assert root.right.right == nil
end
end
test "can create complex tree" do
root =
BinarySearchTree.new(4)
|> BinarySearchTree.insert(2)
|> BinarySearchTree.insert(6)
|> BinarySearchTree.insert(1)
|> BinarySearchTree.insert(3)
|> BinarySearchTree.insert(5)
|> BinarySearchTree.insert(7)
assert root.data == 4
assert root.left.data == 2
assert root.left.left.data == 1
assert root.left.left.left == nil
assert root.left.left.right == nil
assert root.left.right.data == 3
assert root.left.right.left == nil
assert root.left.right.right == nil
assert root.right.data == 6
assert root.right.left.data == 5
assert root.right.left.left == nil
assert root.right.left.right == nil
assert root.right.right.data == 7
assert root.right.right.left == nil
assert root.right.right.right == nil
end
describe "can sort data" do
test "can sort single number" do
root = BinarySearchTree.new(2)
assert [2] == BinarySearchTree.in_order(root)
end
test "can sort if second number is smaller than first" do
root =
BinarySearchTree.new(2)
|> BinarySearchTree.insert(1)
assert [1, 2] == BinarySearchTree.in_order(root)
end
test "can sort if second number is the same as the first" do
root =
BinarySearchTree.new(2)
|> BinarySearchTree.insert(2)
assert [2, 2] == BinarySearchTree.in_order(root)
end
test "can sort if second number is greater than the first" do
root =
BinarySearchTree.new(2)
|> BinarySearchTree.insert(3)
assert [2, 3] == BinarySearchTree.in_order(root)
end
test "can sort complex tree" do
root =
BinarySearchTree.new(2)
|> BinarySearchTree.insert(1)
|> BinarySearchTree.insert(3)
|> BinarySearchTree.insert(6)
|> BinarySearchTree.insert(7)
|> BinarySearchTree.insert(5)
assert [1, 2, 3, 5, 6, 7] == BinarySearchTree.in_order(root)
end
end
end

View File

@ -0,0 +1,2 @@
ExUnit.start()
ExUnit.configure(exclude: :pending, trace: true)