LeetCodeUtils

LeetCodeUtils is a lightweight .NET 8 utility library providing canonical data structures and helper methods commonly used in LeetCode problems.
It includes:

• ListNode (singly linked list)
• TreeNode (binary tree)
• ListNodeUtils (creation, conversion, printing)
• TreeNodeUtils (creation, conversion, pretty‑printing)

Designed for interview prep, algorithm practice, and cleaner LeetCode solutions.

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📦 Install via NuGet

dotnet add package LeetCodeUtils

NuGet: https://www.nuget.org/packages/LeetCodeUtils

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📂 Solution Structure

LeetCodeUtils.sln
│
├── src/
│   ├── LeetCodeUtils/              # Class Library (NuGet package)
│   │   ├── ListNode.cs
│   │   ├── TreeNode.cs
│   │   ├── ListNodeUtils.cs
│   │   └── TreeNodeUtils.cs
│   │
│   └── LeetCodeUtils.Console/      # Console demo
│       └── Program.cs
│
└── tests/
    └── LeetCodeUtils.Tests/        # xUnit test suite
        ├── ListNodeUtilsTests.cs
        └── TreeNodeUtilsTests.cs

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🚀 Getting Started

Build the solution

git clone https://github.com/wblackmon/LeetCodeUtils.git
cd LeetCodeUtils
dotnet build

Run the console demo

dotnet run --project src/LeetCodeUtils.Console

Run tests

dotnet test

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🔗 Usage Examples

Linked List Example

using LeetCodeUtils;

// Create a linked list from an array
var head = ListNodeUtils.FromArray(new[] { 1, 2, 3, 4 });

// Convert back to array
int[] values = ListNodeUtils.ToArray(head);

// Pretty-print the list
Console.WriteLine(ListNodeUtils.ToString(head));
// Output: 1 -> 2 -> 3 -> 4

Binary Tree Example

using LeetCodeUtils;

// Create a binary tree from level-order input
var root = TreeNodeUtils.FromLevelOrder(new int?[] { 1, 2, 3, null, 5 });

// Pretty-print the tree
Console.WriteLine(TreeNodeUtils.ToPrettyString(root));

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🧱 Included Data Structures

ListNode

public class ListNode {
    public int val;
    public ListNode next;
}

TreeNode

public class TreeNode {
    public int val;
    public TreeNode left;
    public TreeNode right;
}

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🔧 Utility Methods

ListNodeUtils

• FromArray(int[])
• ToArray(ListNode)
• ToString(ListNode)
• Append(ListNode, int)
• Reverse(ListNode)

TreeNodeUtils

• FromLevelOrder(int?[])
• ToLevelOrder(TreeNode)
• ToPrettyString(TreeNode)
• Height(TreeNode)
• IsBalanced(TreeNode)

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🧪 Testing

Example xUnit test:

[Fact]
public void ToString_ShouldReturnCorrectFormat()
{
    var head = ListNodeUtils.FromArray(new[] { 1, 2, 3 });
    Assert.Equal("1 -> 2 -> 3", ListNodeUtils.ToString(head));
}

Run tests:

dotnet test

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📦 NuGet Packaging

Build and pack:

dotnet pack src/LeetCodeUtils/LeetCodeUtils.csproj -c Release -o ./artifacts

Publish (Trusted Publishing via GitHub Actions):

dotnet nuget push ./artifacts/*.nupkg \
  --source https://api.nuget.org/v3/index.json \
  --skip-duplicate

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🏗️ Roadmap

• PrettyPrint ASCII renderer for binary trees
• Random linked list & tree generators
• Additional conversion helpers
• Expanded test coverage

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📜 License

MIT License © Wayne Eliot Blackmon