Write a function that counts the number of primes in the
range [1-N]. Write the test cases for this function.
- 2 Answers
- 17505 Views
- Microsoft, I also Faced
- E-Mail Answers
Answer Posted / softwareguy
This is what I came up with (C#):
PSEUDO:
-Craete a list of numbers uptill n number - n being int
parameter
-Pass this list into a function to check for primilaty for
the number and then print primes wile we count for primes
BACKGROUND OF THIS SOLUTION:
THEORY:
- we know primes are the numbers starting from 2 are
divisible with 1 and themselves only i.e. n being a prime
number can only be divisble as n/n or n/1. testing from a
prime is called "primilatiy test" for a number...
-the simplest primality test is to see if given a number n
is divisible by an integer m from 2 to n-1. If n is
divisible by n then n is a composite number otherwise its a
prime...
TO SPEED UP THE COMPUTING WE CAN ALSO:
Rather than testing till n-1 we can test the number till
Square Root of n i.e. if n is a prime number it can always
be factored into 2 values.
REFERENCE:
See here if you want to be a mathematician ;-).
http://en.wikipedia.org/wiki/Primality_test
THE CODE:
I would assume you know how to deal with lists in c# so I
will not get into that. Just create an integer based items
list "list<int>" etc. in C# which adds digits to the list
till number n. HINT: use a for loop ...LOL!!
public void CountPrimes(list<int> c)
{
list<int> primes = c.FindAll(
delegate(int a)
for (int i = 2; i <= Math.Sqrt(a); i++)
{
if (a % i == 0)
return false; //is not a prime
return true;//is a prime
}
//list primes in a list box and get the total count
label1.Text = "Total Primes = " + Convert.ToString
(p.count);
for (int count = 2; count < p.count; count++)
{
listbox.Items.Add(Convert.ToString(p[i]));
}
}
and you are done!!! let me know if this is good enough...
| Is This Answer Correct ? | 1 Yes | 4 No |
Post New Answer View All Answers
What training have you undergone in project planning?
How did you choose the appropriate lifecycle for your project?
how to tell project details in interview the project is funds flow analysis?
Please, i am a final year student in nigeria and i have a project on pension fund administration and i need help in starting.
Tell about yourself and job ?
Write the test cases for instr function?
Can any one please give me an effective format for designing a functional specification and technical specification sheet for a software developemnt related company asap...it would be highly useful for my final year project.
How would you deal with a bug that no one wants to fix? Both the SDE and his lead have said they won?t fix it?
Did you used crystal reports? Do you have sufficient knowledge on crystal reports?
Tell about current project ?
How do you create the Software Project Management Plan (SPMP)?
Write the instr function.
Test the save dialog in Notepad?
What is the role of CLR in ASP.NET?
Why do you want to work for Microsoft?
