Pythagorean triples: Difference between revisions

Content added Content deleted

Inline

@@ Line 461: / Line 461: @@
 First up is a fairly naive brute force implementation that is not really practical for large perimeter limits. 100 is no problem. 1000 is slow. 10000 is glacial.
-Works with Rakudo 11.06.
+Works with Rakudo 2011.06.
-<lang perl6>my %trips;
+<lang perl6>my %triples;
 my $limit = 100;
 for 3 .. $limit/2 -> $c {
-   for 1 .. $c-1 -> $a {
+   for 1 .. $c -> $a {
-       my $b = ($c ** 2 - $a **2).sqrt;
+       my $b = ($c * $c - $a * $a).sqrt;
        last if $c + $a + $b > $limit;
+       last if $a > $b;
        if $b == $b.Int {
-          my $key = ~($a, $b, $c).sort;
+          my $key = "$a $b $c";
-          next if %trips.exists($key);
+          %triples{$key} = ([gcd] $c, $a, $b.Int) > 1 ?? 0  !! 1;
-          %trips{$key} = ([gcd] $c, $a, $b.Int) > 1 ?? 0  !! 1;
+          say $key, %triples{$key} ?? ' - primitive' !! '';
        }
    }
 }
-say "There are {+%trips} Pythagorean Triples with a perimeter less than $limit,"
+say "There are {+%triples.keys} Pythagorean Triples with a perimeter <= $limit,"
- ~" of which {[+] %trips.values} are primitive.";
+ ~"\nof which {[+] %triples.values} are primitive.";</lang>
+<pre>3 4 5 - primitive
-for %trips.keys.sort( {$^a.lc.subst(/(\d+)/,->$/{0~$0.chars.chr~$0},:g)} ) -> $k {
+8 10
-    say $k.fmt("%14s"), %trips{$k} ?? ' - primitive' !! '';
+12 13 - primitive
-}</lang>
+12 15
+15 17 - primitive
-<pre>There are 17 Pythagorean Triples with a perimeter less than 100, of which 7 are primitive.
+16 20
-4 5 - primitive
-12 13 - primitive
+24 25 - primitive
+20 25
-8 10
+24 26
-24 25 - primitive
-15 17 - primitive
+21 29 - primitive
+24 30
-12 15
+30 34
-40 41 - primitive
+28 35
-24 26
+35 37 - primitive
-16 20
+36 39
-35 37 - primitive
+32 40
-20 25
+40 41 - primitive
-36 39
+There are 17 Pythagorean Triples with a perimeter <= 100,
-30 34
+of which 7 are primitive.
-24 30
+</pre>
-21 29 - primitive
-28 35
-32 40</pre>
 Here's a much faster version.  Hint, "oyako" is Japanese for "parent/child". <tt>:-)</tt>
 {{works with|niecza}}