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https://github.com/sunil-kumarr/lastcode

A sleek, terminal-based interactive visualizer for tree, graph, grid, and array algorithms.
https://github.com/sunil-kumarr/lastcode

arrays dsa-algorithm dsa-learning-series dsa-practice graph-algorithms interview-preparation interview-questions leetcode neetcode python queue stack string terminal terminal-ui

Last synced: 5 days ago
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A sleek, terminal-based interactive visualizer for tree, graph, grid, and array algorithms.

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README 

          
# 🌌 lastcode



> A sleek, terminal-based interactive visualizer for tree, graph, grid, and array algorithms. Built with Python and the [Textual](https://github.com/Textualize/textual) framework.



`lastcode` allows you to trace, step-through, and animate classic coding interview problems directly in your terminal with beautiful ANSI visuals, real-time variable inspection, a code stepper, and step-by-step explanations.



---



## ✨ Features

lastcode tree visualizer screenshot

lastcode grid visualizer screenshot

lastcode array visualizer screenshot



* **Interactive ASCII Renderers**: Visualized trees, grids, and arrays respond dynamically as the algorithm executes.

* **Trace-Driven Replay**: Leverages Python's execution tracing (`sys.settrace`) to record and reconstruct step-by-step algorithm states.

* **Variable Inspector & Legend Panel**: Keeps track of current variables, recursions, pointers, and color-coded state transitions.

* **Integrated Code Stepper**: Highlights the exact line of Python code running at each step of execution.

* **Custom Input Support**: Modify tree structures, grid dimensions, and array contents live in the application using standard format notation.

* **Hot-Reloading Dev Runner**: Active development watcher watches `.py` and `.css` files and restarts the TUI instantly on change.



---



## 🎨 Color Palette & Themes

The visualizer runs a sleek, modern Tokyonight-inspired aesthetic:

* 🌌 **Background**: `#252836` & `#1E2230`

* ⚡ **Accent Blue**: `#7AA2F7`

* đŸŒŋ **Success Green**: `#9ECE6A`

* 🔸 **Warning/Pointer Yellow**: `#E0AF68`

* 🌹 **Critical/Path Red**: `#F7768E`



---



## 🚀 Installation & Getting Started



### Prerequisites

* **Python**: `>=3.11`

* **Package Manager**: `brew`, `pipx`, `pip`, or `uv`



### Option 1: macOS Homebrew (Recommended)

The cleanest way to install on macOS without interacting with system Python environments or virtual environments.



```bash

# 1. Tap the repository

brew tap sunil-kumarr/tap



# 2. Install the application cleanly

brew install lastcode-tui

```



### Option 2: via PyPI (`pipx` or `pip`)

Because modern operating systems enforce environment protections (PEP 668), installing standalone global terminal applications via standard `pip install` will often fail. Use `pipx` to run the tool in an isolated sandbox.



```bash

# Recommended for global installation:

pipx install lastcode-tui



# Alternatively, run instantly using uv without permanent installation:

uvx lastcode-tui

```



### Option 3: Local Development (Source Build)

If you are planning to contribute or modify the visualizer core:



1. Clone the repository:

   ```bash

   git clone https://github.com/sunil-kumarr/lastcode.git

   cd lastcode

   ```



2. Create and activate a virtual environment:

   ```bash

   python3 -m venv .venv

   source .venv/bin/activate

   ```



3. Install the package in editable mode:

   ```bash

   pip install -e .

   ```



---



## 🕹ī¸ Usage



### Run the Visualizer

Once installed via any option above, start the interactive engine from anywhere in your terminal:

```bash

lastcode

```



For a local source checkout, you can also run the module directly:

```bash

python -m lastcode

```



### Hot-Reloading for Development

If you are modifying code, stylesheets, or adding new problems, run the watcher script inside your source directory. It will instantly reload the application in the terminal when changes are saved:

```bash

python dev.py

```



---



## 🎮 Keybindings & Controls



### 🏠 Home / Menu Screen

| Key | Action |

| :--- | :--- |

| `↑` / `↓` | Navigate the problem list |

| `t` | Cycle topic filters (*tree, grid, graph, array, string, dp*) |

| `d` | Cycle difficulty filters (*easy, medium, hard*) |

| `Enter` | Launch the selected visualizer |

| `q` | Quit application |



### 🛠ī¸ Visualizer Screen

| Key | Action |

| :--- | :--- |

| `→` / `l` | **Step Forward** to the next execution frame |

| `←` / `h` | **Step Backward** to the previous execution frame |

| `Space` | **Play / Pause** auto-playback animation |

| `i` | **Edit Input** (Focuses input field to provide custom data structures) |

| `Enter` | **Submit** custom input (Parses, validates, and runs the visualizer on your input) |

| `Escape` | **Home / Cancel** input edit and return to main menu |

| `q` | **Quit** application |



---



## 🎛ī¸ Custom Input Formats



You can press `i` on any visualization screen to customize the input. Values are parsed securely using Python's `ast.literal_eval`.



### đŸŒŗ Binary Trees

Binary trees are represented using level-order lists.

* **Simple Binary Tree**: `[1, 2, 3, None, 4]` (representing a tree with root `1`, children `2` and `3`, and leaf `4` on the right of `2`).

* **Path-Sum Tree Problems**: `([1, 2, 3], 4)` (a tuple containing the tree array and target integer).

* *Note: Maximum tree size supported is 31 nodes.*



### đŸ—ēī¸ Grids (Count Islands)

Grids are parsed as 2D lists of `0`s (water) and `1`s (land).

* **Format**: `[[1, 1, 0], [0, 1, 0], [1, 0, 1]]` (all rows must have equal width).



### đŸ”ĸ Arrays & Strings

* **Two Sum**: `[2, 7, 11, 15], 9` (the array part, followed by a comma and target sum).

* **Valid Parentheses**: `(){}[]` (a simple string of bracket characters).



---



## 📂 Project Structure



```text

lastcode/

├── dev.py                    # Hot-reloading watcher script

├── pyproject.toml            # Project dependencies and script endpoints

├── lastcode/

│   ├── main.py               # Main entrypoint

│   ├── app.py                # Main visualizer screens and layout controllers

│   ├── home.py               # Home screen widgetry and filters

│   ├── recorder.py           # Core logic tracer (tracks call frames and values)

│   ├── theme.py              # Central design-system colors

│   ├── problems/             # Interactive problems repository

│   │   ├── registry.py       # Problem metadata & path registration

│   │   ├── bt_inorder.py     # Binary Tree Inorder Traversal

│   │   ├── count_islands.py  # Count Islands

│   │   └── ... (20+ algorithm modules)

│   ├── renderers/            # UI renderers

│   │   ├── base.py           # Renderer protocol definitions

│   │   ├── tree.py           # Tree structure layout & animation renderer

│   │   ├── grid.py           # 2D Grid DFS/BFS layout renderer

│   │   └── array.py          # 1D Array tracker & stack renderer

│   └── widgets/              # Reusable textual widgets

│       └── ...               # Scrubber bars, Legend keys, variable drawers

```



---



## 📝 License

This project is licensed under the MIT License.