Files
ioccc/2000/bellard

Most Specific Output

Fabrice Bellard
451 chemin du mas de Matour
34790 Grabels
France
https://bellard.org

To build:

make

To run:

./bellard

Try:

Do. Or do not. There is no try. :-)

Judges' remarks:

This code is a nice compact example of a Modular Fast Fourier Transform. While its output is very specific, the internal FFT has a wide variety of uses.

Can you modify this code to produce primes such as 23523*2^70000-1, 48594^65536+1 or 6917!-1?

NOTE: as bigger primes are found as time goes by this program no longer prints the biggest prime once noted by the author below.

Author's comments:

This program prints the biggest known prime number (2^6972593-1) in base 10. It requires a few minutes. It uses a Modular Fast Fourier Transform to compute this number in a reasonable amount of time (the usual method would take ages !).

The program uses >= 64 bit 'long long' type. It should run on any system with a gcc compiler.

This file is Copyright (c) 2023 by Landon Curt Noll. All Rights Reserved. You are free to share and adapt this file under the terms of this license:

Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)

For more information, see: https://creativecommons.org/licenses/by-sa/4.0/