NodePipeline/NodePipeline.Engine/Graph/CycleDetector.cs

namespace NodePipeline.Engine.Graph;

public static class CycleDetector
{
    public static bool HasCycle(Dictionary<string, List<string>> graph)
    {
        var visited = new HashSet<string>();
        var inStack = new HashSet<string>();

        foreach (var node in graph.Keys)
            if (Dfs(node))
                return true;

        return false;

        bool Dfs(string current)
        {
            if (inStack.Contains(current)) return true;

            if (!visited.Add(current)) return false;

            inStack.Add(current);
            foreach (var next in graph[current])
                if (Dfs(next))
                    return true;

            inStack.Remove(current);
            return false;
        }
    }
}