Question

The server must maintain data for last n days. It must show the most visited pages of the current day first and then the most visited pages of next day and so on.

I’m thinking along the lines of hash map of hash maps. Any suggestions ?

Answer 1

Outer hash map with key of type date and value of type hash map.

Inner hash map with key of type string containing the url and value of type int containing the visit count.

Example in C#:

// Outer hash map    
var visitsByDay = 
    new Dictionary<DateTime, VisitsByUrl>(currentDate, new VisitsByUrl());

...

// inner hash map
public class VisitsByUrl
{
    public Dictionary<string, int> Urls { get; set; }

    public VisitsByUrl()
    {
        Urls = new Dictionary<string, int>();
    }

    public void Add(string url)
    {
        if (Urls[url] != null)
            Urls[url] += 1;
        else
            Urls.Add(url, 1);
    }
}