- Added solutions by Kevin Colyer.

2 files changed, 107 insertions, 0 deletions

diff --git a/challenge-027/kevin-colyer/perl6/ch-1.p6 b/challenge-027/kevin-colyer/perl6/ch-1.p6
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+++ b/challenge-027/kevin-colyer/perl6/ch-1.p6
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+#!/usr/bin/perl6
+use v6;
+
+use Test;
+
+# 27.1 Write a script to find the intersection of two straight lines. The co-ordinates of the two lines should be provided as command line parameter. For example:
+#
+# The two ends of Line 1 are represented as co-ordinates (a,b) and (c,d).
+#
+# The two ends of Line 2 are represented as co-ordinates (p,q) and (r,s).
+#
+# The script should print the co-ordinates of point of intersection of the above two lines.
+
+#| Prints intersection point of two lines given as 1,2,3,4   5,6,7,8
+multi MAIN(Str $line1,Str $line2) {
+    my ($meet,$x,$y,$comment) = intersection(| $line1.split(','), | $line2.split(','));
+    say $meet ?? "$x,$y" !! $comment;
+    exit;
+}
+
+sub intersection($a,$b,$c,$d,$e,$f,$g,$h) {
+    # line 1 a,b -> c,d
+    # line 2 e,f -> g,h
+
+    my $m1=($b-$d)/($a-$c);
+    my $m2=($f-$h)/($e-$g);
+
+    return (False,Nil,Nil,"Do not intersect: lines are parallel") if $m1==$m2;
+
+    # y=dydx1.x-dydx1.a+b == y=dydx2.x-dydx2.e+f
+
+    # x=dydx1.a-b/dydx1
+    # wrong worong worng my $x=($m1*$a-$b)/$m1;
+
+    my $x=($f-$b+$m1*$a-$m2*$e)/($m1-$m2);
+
+    my $y=$m2*$x-$m2*$e+$f;
+
+    return (False,Nil,Nil,"Do not intersect: x is not on line 1") if $x < $a < $c or $x > $c > $a;
+    return (False,Nil,Nil,"Do not intersect: y is not on line 1") if $y < $b < $d or $y > $d > $b;
+    return (False,Nil,Nil,"Do not intersect: x is not on line 2") if $x < $e < $g or $x > $g > $e;
+    return (False,Nil,Nil,"Do not intersect: y is not on line 2") if $y < $f < $h or $y > $h > $f;
+
+    return (True,$x,$y,"Lines intersect at $x,$y");
+
+}
+
+multi MAIN('test') {
+    my ($meet,$x,$y,$comment) = intersection(1,1,3,3, 1,3,3,1);
+    is $meet,True,"Test A - lines meet";
+    is $x,2,"Test A - lines meet - x";
+    is $y,2,"Test A - lines meet - y";
+    diag $comment;
+    ($meet,$x,$y,$comment) = intersection(1,1,3,3, 1,2,3,4);
+    is $meet,False,"Test A - lines meet";
+    diag $comment;
+    ($meet,$x,$y,$comment) = intersection(1,1,3,3, 4,3,6,1);
+    is $meet,False,"Test A - lines meet";
+    diag $comment;
+    ($meet,$x,$y,$comment) = intersection(1,1,3,3, 1,1,3,3);
+    is $meet,False,"Test D - lines are parallel";
+
+
+    done-testing;
+}
diff --git a/challenge-027/kevin-colyer/perl6/ch-2.p6 b/challenge-027/kevin-colyer/perl6/ch-2.p6
new file mode 100644
index 0000000000..dcf793c848
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+++ b/challenge-027/kevin-colyer/perl6/ch-2.p6
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+#!/usr/bin/perl6
+use v6;
+
+use Test;
+
+# 27.2 Write a script that allows you to capture/display historical data. It could be an object or a scalar. For example
+#
+# my $x = 10; $x = 20; $x -= 5;
+#
+# After the above operations, it should list $x historical value in order.
+
+# with ideas from https://stackoverflow.com/questions/31665384/how-does-one-write-custom-accessor-methods-in-perl6
+class HistoryInt {
+  has Int $.x =0 ;
+  has @.history;
+
+  # overwrite the method the attribute declaration added
+  method x () is rw {
+    Proxy.new(
+      FETCH => -> $ { $!x },
+      STORE => -> $, Int $new {
+        $!x = $new;
+        @!history.push: $new;
+      }
+    )
+  }
+  method History () {
+    @!history;
+  }
+}
+
+my $h=HistoryInt.new();
+
+$h.x=10;
+is $h.History,(10),"list of first op";
+$h.x=20;
+is $h.History,(10,20),"list of ops";
+$h.x-=5;
+is $h.History,(10,20,15),"list of ops";
+
+done-testing;
+