Tell about one or two interesting technical tasks you solved in previous projects.

In one of my projects, I had to implement a data caching system for an API to reduce the load on the database and speed up the service response. I used the "Lazy Loading" pattern and implemented a cache with automatic refresh via a timer.

Example code in C#:

public class DataCache
{
    private Dictionary<string, object> _cache = new Dictionary<string, object>();
    private Timer _timer;

    public DataCache()
    {
        _timer = new Timer(RefreshCache, null, TimeSpan.Zero, TimeSpan.FromMinutes(10));
    }

    private void RefreshCache(object state)
    {
        // Cache refresh logic
    }

    public object GetData(string key)
    {
        if (_cache.ContainsKey(key))
            return _cache[key];
        // Load data and add to cache
    }
}

I also solved the problem of optimizing multithreaded access to shared resources using lock and Concurrent collections.