Merge pull request #2387 from tedleahy/master

Add solutions for week 79

2 files changed, 96 insertions, 0 deletions

diff --git a/challenge-079/ted-leahy/ch-1.pl b/challenge-079/ted-leahy/ch-1.pl
new file mode 100644
index 0000000000..45f876c25a
--- /dev/null
+++ b/challenge-079/ted-leahy/ch-1.pl
@@ -0,0 +1,25 @@
+# # Count Set Bits # #
+# - You are given a positive number $N.
+# - Write a script to count the total numbrer of set bits of the binary representations
+#   of all numbers from 1 to $N and return $total_set_bit_count % 1000000007.
+# #
+
+use strict;
+use warnings;
+use feature 'say';
+
+my ($N) = @ARGV;
+my $total_set_bit_count = 0;
+
+foreach my $n (1..$N) {
+    # Convert to binary
+    my $binary_n = sprintf("%b", $n);
+    # Count the number of set bits ('1's)
+    my $set_bit_count = ($binary_n =~ tr/1//);
+
+    $total_set_bit_count += $set_bit_count;
+}
+
+say $total_set_bit_count % 1000000007;
+
+1;
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diff --git a/challenge-079/ted-leahy/ch-2.pl b/challenge-079/ted-leahy/ch-2.pl
new file mode 100644
index 0000000000..e4b511a944
--- /dev/null
+++ b/challenge-079/ted-leahy/ch-2.pl
@@ -0,0 +1,71 @@
+# # Trapped Rain Water # #
+# You are given an array of positive numbers @N.
+# Write a script to represent it as Histogram Chart and find out how much 
+# water it can trap.
+# #
+
+use strict;
+use warnings;
+use feature 'say';
+
+use List::Util qw(min max);
+
+my @N = @ARGV;
+
+print_histogram(@N);
+
+my $total_trapped_water = amount_of_trapped_water(@N);
+say "\nTotal amount of trapped water: $total_trapped_water";
+
+sub print_histogram {
+    my (@N) = @_;
+
+    my @y_axis = reverse (1..max(@N));
+
+    foreach my $y_value (@y_axis) {
+        print "$y_value ";
+
+        foreach my $x_value (@N) {
+            print $y_value <= $x_value ? '#' : ' ';
+            print ' ';
+        } 
+
+        print "\n";
+    }
+
+    say '- ' x scalar @N + 1;
+    say '  ' . join(' ', @N);
+}
+
+# take the first number, then walk along the array until you find a number
+# that's greater than or equal to it.
+# then take all the numbers in between them, and for each one:
+#   subtract that from the second number,
+#   add that to $total_rain_units
+# keep going until you reach the end of the array
+
+sub amount_of_trapped_water {
+    my (@N) = @_;
+
+    my $total_rain_units = 0;
+    my $left_col_index = 0;
+    
+    for my $i (0..$#N) {
+        my $current_col = $N[$i];
+        my $left_col = $N[$left_col_index];
+    
+        if ($current_col >= $left_col) {
+            my $smaller_side = min($left_col, $current_col);
+        
+            foreach ($left_col_index+1..$i-1) {
+                $total_rain_units += ($smaller_side - $N[$_]);
+            }
+        
+            $left_col_index = $i; 
+        }
+    }
+
+    return $total_rain_units
+}
+
+1;
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