Question

I was posed this question at an interview and never really came up with a great solution. Does anyone have an “optimum” solution? Where the target is efficiency and being able to deal with large input.

Material Provided:

I am given a long list of shops and their opening/closing times (say 1000).

The Problem:

For a given time of day, return how many of the shops are open

Example Data:

Sainsburys 10:00 23:00
Asda 02:00 18:00
Walmart 17:00 22:00

Example In/Out

Input | Output
12:00 | 2
22:00 | 1 (walmart shut @ 22:00)
17:30 | 3

The two parts of the problem are how to store the data and how to efficiently get the answer, I guess how you’re reading the input etc doesn’t really matter.

Thanks for your time and insight!

Answer 1

Let’s take a stab:

//First, we turn the time input into an int and then compare it to the open and
//closing time ints to determine if the shop is open. We'l use 10:00 in this example.
//get magic time int
int magicTimeInt = CInt("10:00".Replace(":",""));
int openstorecount = 0;
foreach(var shoptime in ShopTimesList)//SHopTImesList is the list of shop names and times
{
    string[] theShop = shoptime.Split(" ");
    if( CInt(theshop[1].ToString().Replace(":", "")) < magicTimeInt 
    && 
    CInt(theshop[2].ToString().Replace(":", "")) > magicTimeInt)
    {
        openstorecount++;
    }
}
Console.WriteLine("10:00 | " + openstorecount.ToString());