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- #!/usr/bin/perl
- # Author: Daniel "Trizen" Șuteu
- # License: GPLv3
- # Date: 25 August 2016
- # Website: https://github.com/trizen
- # https://projecteuler.net/problem=231
- # Runtime: 1.583s
- use 5.020;
- use strict;
- use warnings;
- use experimental qw(signatures);
- use ntheory qw(forprimes vecsum todigits);
- sub factorial_power ($n, $p) {
- ($n - vecsum(todigits($n, $p))) / ($p - 1);
- }
- my $n = 20000000;
- my $k = 15000000;
- my $j = $n - $k;
- my $sum = 0;
- forprimes {
- my $p = factorial_power($n, $_);
- if ($_ <= $k) {
- $p -= factorial_power($k, $_);
- }
- if ($_ <= $j) {
- $p -= factorial_power($j, $_);
- }
- $sum += $p * $_;
- } $n;
- say $sum;
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