- Added Raku solution to "Trapped Rain Water" task.

2 files changed, 177 insertions, 0 deletions

diff --git a/challenge-079/mohammad-anwar/raku/ch-2.raku b/challenge-079/mohammad-anwar/raku/ch-2.raku
new file mode 100644
index 0000000000..1376f46827
--- /dev/null
+++ b/challenge-079/mohammad-anwar/raku/ch-2.raku
@@ -0,0 +1,100 @@
+#!/usr/bin/env raku
+
+#
+# Perl Weekly Challenge - 079
+#
+# Task #2: Trapped Rain Water
+#
+# https://perlweeklychallenge.org/blog/perl-weekly-challenge-079
+#
+
+use v6.d;
+
+subset PositiveInt of Int where * >= 0;
+
+sub MAIN(*@N where @N.elems > 1 && all(@N) ~~ PositiveInt) {
+    chart(@N).say;
+    trapped-rain-water(@N).say;
+}
+
+#
+#
+# SUBROUTINES
+
+sub trapped-rain-water(*@array where .all ~~ PositiveInt) {
+
+    my @a   = ();
+    my $p   = 0;
+    my $trw = 0;
+    for @array -> $n {
+        if $p == 0 || $p >= $n {
+            $p = $n if @a == 0 || ($p == 0 && $n > $p);
+            @a.push: $n;
+        }
+        else {
+            @a.push: $n;
+            $trw += fetch-trapped-water(@a);
+            @a = $n;
+            $p = $n if $p < $n;
+        }
+    }
+
+    # are there any left over to be processed?
+    if @a.elems > 1 {
+        $trw += fetch-trapped-water(@a);
+    }
+
+    return $trw;
+}
+
+sub fetch-trapped-water(*@array where .all ~~ PositiveInt) {
+
+    # remove any smaller tower from the start
+    repeat {
+        if @array[0] == 0 {
+            @array.shift;
+        }
+    } until @array[0] > 0;
+
+    # remove any smaller tower from the end
+    repeat {
+        if @array[*-1] < @array[*-2] {
+            @array.pop;
+        }
+    }
+    until @array[*-1] > @array[*-2];
+
+    my $max = (@array[0], @array[*-1]).min * (@array.elems - 2);
+    $max -= @array[$_] for 1..@array.elems - 2;
+
+    return $max;
+}
+
+sub chart(*@list where @list.elems > 1 && all(@list) ~~ PositiveInt --> Str) {
+
+    my $max   = @list.max;
+    my $chart = [];
+    my $row   = 1;
+    for 1 .. $max -> $n {
+        my Str $data = "";
+        for 0 .. @list.elems-1 -> $i {
+            if $row <= @list[$i] {
+                $data ~= " #";
+            }
+            else {
+                $data ~= "  ";
+            }
+        }
+
+        $row += 1;
+
+        $chart.push: sprintf("%d%s", $n, $data);
+    }
+
+    my (Str $histogram, Str $line, Str $size) = ("", "", "  ");
+    $histogram = $chart.reverse.join("\n");
+    $line ~= "_ " for 0 .. @list.elems;
+    $size ~= @list.join(" ");
+
+    return ($histogram, $line, $size).join("\n");
+}
diff --git a/challenge-079/mohammad-anwar/raku/ch-2.t b/challenge-079/mohammad-anwar/raku/ch-2.t
new file mode 100644
index 0000000000..cf6d6951a7
--- /dev/null
+++ b/challenge-079/mohammad-anwar/raku/ch-2.t
@@ -0,0 +1,77 @@
+#!/usr/bin/env raku
+
+#
+# Perl Weekly Challenge - 079
+#
+# Task #2: Trapped Rain Water
+#
+# https://perlweeklychallenge.org/blog/perl-weekly-challenge-079
+#
+
+use Test;
+
+subset PositiveInt of Int where * >= 0;
+
+is trapped-rain-water(0, 1, 2, 3, 4, 5),
+   0, "testing: 0, 1, 2, 3, 4, 5";
+is trapped-rain-water(3, 1, 3, 1, 1, 5),
+   6, "testing: 3, 1, 3, 1, 1, 5";
+is trapped-rain-water(2, 1, 4, 1, 2, 5),
+   6, "testing: 2, 1, 4, 1, 2, 5";
+is trapped-rain-water(0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1),
+   6, "testing: 0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1";
+
+done-testing;
+
+#
+#
+# SUBROUTINES
+
+sub trapped-rain-water(*@array where .all ~~ PositiveInt) {
+
+    my @a   = ();
+    my $p   = 0;
+    my $trw = 0;
+    for @array -> $n {
+        if $p == 0 || $p >= $n {
+            $p = $n if @a == 0 || ($p == 0 && $n > $p);
+            @a.push: $n;
+        }
+        else {
+            @a.push: $n;
+            $trw += fetch-trapped-water(@a);
+            @a = $n;
+            $p = $n if $p < $n;
+        }
+    }
+
+    # are there any left over to be processed?
+    if @a.elems > 1 {
+        $trw += fetch-trapped-water(@a);
+    }
+
+    return $trw;
+}
+
+sub fetch-trapped-water(*@array where .all ~~ PositiveInt) {
+
+    # remove any smaller tower from the start
+    repeat {
+        if @array[0] == 0 {
+            @array.shift;
+        }
+    } until @array[0] > 0;
+
+    # remove any smaller tower from the end
+    repeat {
+        if @array[*-1] < @array[*-2] {
+            @array.pop;
+        }
+    }
+    until @array[*-1] > @array[*-2];
+
+    my $max = (@array[0], @array[*-1]).min * (@array.elems - 2);
+    $max -= @array[$_] for 1..@array.elems - 2;
+
+    return $max;
+}