Express any number as the sum of 4 prime numbers [Doubts]

Posted by WarDoGG on Stack Overflow See other posts from Stack Overflow or by WarDoGG
Published on 2010-04-30T11:29:47Z Indexed on 2010/04/30 12:07 UTC
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math

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c++

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algorithm

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homework

I was give a problem to express any number as sum of 4 prime numbers.

Conditions:

Not allowed to use any kind of database.
Maximum execution time : 3 seconds
Numbers only till 100,000
If the splitting is NOT possible, then return -1

What i did :

using the sieve of eratosthenes, i calculated all prime numbers till the specified number.
looked up a concept called goldbach conjecture which expresses an even number as the summation of 2 primes.

However, i am stuck beyond that. Can anyone help me on this one as to what approach u might take ?

The sieve of eratosthenes is taking 2 seconds to count primes till 100,000 :(((

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