done Task 1

1 files changed, 82 insertions, 16 deletions

diff --git a/challenge-169/cheok-yin-fung/perl/ch-1.pl b/challenge-169/cheok-yin-fung/perl/ch-1.pl
index 35de02700c..5a82cb55f9 100644
--- a/challenge-169/cheok-yin-fung/perl/ch-1.pl
+++ b/challenge-169/cheok-yin-fung/perl/ch-1.pl
@@ -1,34 +1,100 @@
 #!/usr/bin/perl
 # The Weekly Challenge 169
-# Task 1 Brilliant Numbers
+# Task 1 Brilliant Numbers Version 3.0
+# See https://e7-87-83.github.io/coding/challenge_169.html
+#  for a simpler version, up to first 241 brilliant numbers
+
+=pod DATA
+    number of 1-digit primes =    4
+    number of 2-digit primes =   21
+    number of 3-digit primes =  143
+    number of 4-digit primes = 1061
+    number of brilliant numbers from 1-digit primes =      10
+    number of brilliant numbers from 2-digit primes =     231
+    number of brilliant numbers from 3-digit primes =   10296  #OEIS limit
+    number of brilliant numbers from 4-digit primes =  563391
+=cut
+
 use v5.24.0;
-use warnings;
+no warnings;
+use Math::Prime::Util qw/forprimes/;
+use POSIX;
 
-my $req = $ARGV[0] || 20;
+if (defined($ARGV[0])) {
+    say bn($ARGV[0]);
+}
+else {
+    say bn(20);
+}
 
-my @prime = (2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 
-             41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97);
 
-die "You're asking too many, or I am too little!\n" 
-    if $req > 241;  # 21*20/2 +  21 + 4*3/2 + 4
 
+sub bn {
+    my $req = $_[0];
+    my $show_all_values = $req <= 50; 
+    # show all values if the required number is small
 
-my $pt = ceil( ( sqrt(8*$req-79) +7 )/2 ) - 1;
+    my %prime = (1 => [2, 3, 5, 7],
+                 2 => [11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 
+                       47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97],
+                 3 => [],
+                 4 => [],
+                );
 
-my @brilliant = (-1, 4, 6, 9, 10, 14, 15, 21, 25, 35, 49);
+    my $digit_len;
 
-my @temp;
+    given ($req) {
+        $digit_len = 1 when $_ <= 10;
+        $digit_len = 2 when $_ > 10 && $_ <= 241;
+        $digit_len = 3 when $_ > 241 && $_ <= 10537;
+        $digit_len = 4 when $_ > 10537 && $_ <= 573928;
+        die "You're asking too many!\n" when $_ > 573928;
+    }
 
+    eval { forprimes {push $prime{3}->@*, $_}  100, 999; } if $digit_len >= 3; 
+    eval { forprimes {push $prime{4}->@*, $_} 1000,9999; } if $digit_len >= 4;
 
-for my $i (4..$pt) {
-    for my $j ($i..24) {
-        my $product = $prime[$i]*$prime[$j];
-        push @temp, $product;
+    my $ind = $req;
+    $ind = $req-10 if $digit_len == 2;
+    $ind = $req-241 if $digit_len == 3;
+    $ind = $req-10537 if $digit_len == 4;
+    my $c = 3;
+    $c = ceil( ( sqrt(8*$ind+1) - 1 ) / 2 ) - 1;
+
+    my @temp;
+
+    for my $i (0..$c) {
+        for my $j ($i..scalar $prime{$digit_len}->@* - 1) {
+            my $product = $prime{$digit_len}[$i]*$prime{$digit_len}[$j];
+            push @temp, $product;
+        }
     }
+    @temp = sort {$a<=>$b} @temp;
+    if ($show_all_values) {
+        my @brilliant = (-1, 4, 6, 9, 10, 14, 15, 21, 25, 35, 49);
+        push @brilliant, @temp;
+        say join "\n", @brilliant[1..$req];
+        return;
+    }
+    return $temp[$ind-1];
 }
 
-push @brilliant, sort {$a<=>$b} @temp;
 
-say join ", ", @brilliant[1..$req];
 
+use Test::More tests=> 13;
+ok bn(60) == 841;
+ok bn(80) == 1079;
+ok bn(100) == 1369;
+ok bn(120) == 1763;
+ok bn(140) == 2231;
+ok bn(160) == 2809;
+ok bn(241) == 9409;
+ok bn(5000) == 197503;
+ok bn(10000) == 696191;
+ok bn(10416) == 851927;
+ok bn(10537) == 994009;
+ok bn(10538) == 1009*1009;
+ok bn(573928) == 9973*9973;
+
+# ref: OEIS:A078972