Solutions to challenge-079.

2 files changed, 107 insertions, 0 deletions

diff --git a/challenge-079/wanderdoc/perl/ch-1.pl b/challenge-079/wanderdoc/perl/ch-1.pl
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+#!perl
+use strict;
+use warnings FATAL => qw(all);
+
+=prompt
+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_count_set_bit % 1000000007.
+
+Example 1: Input: $N = 4 Total set bit count: 1 + 1 + 2 + 1 = 5
+Output: Your script should print `5` as `5 % 1000000007 = 5`.
+
+
+Example 2: Input: $N = 3 Total set bit count: 1 + 1 + 2 = 4
+Output: Your script should print `4` as `4 % 1000000007 = 4`.
+
+=cut
+use Test::More;
+
+sub count_set_bits
+{
+     my $num = $_[0];
+     my $set_bits = 0;
+     for my $i ( 1 .. $num )
+     {
+
+          my $binary = sprintf("%b", $i);
+          $set_bits += $binary =~ tr/1/1/;
+     }
+     return $set_bits;
+}
+is(count_set_bits(4), 5, 'Example 1');
+is(count_set_bits(3), 4, 'Example 2');
+
+done_testing();
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diff --git a/challenge-079/wanderdoc/perl/ch-2.pl b/challenge-079/wanderdoc/perl/ch-2.pl
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+#!perl
+use strict;
+use warnings FATAL => qw(all);
+
+=prompt
+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.
+Example 1: Input: @N = (2, 1, 4, 1, 2, 5)
+Looking at the above histogram, we can see, it can trap 1 unit of rain water between 1st and 3rd column. Similary it can trap 5 units of rain water betweem 3rd and last column. Therefore your script should print 6.
+
+Example 2
+Input: @N = (3, 1, 3, 1, 1, 5)
+Looking at the above histogram, we can see, it can trap 2 units of rain water between 1st and 3rd column. Also it can trap 4 units of rain water between 3rd and last column.
+
+Therefore your script should print 6.
+=cut
+
+use List::Util qw(min max);
+
+sub print_histogram # Challenge 075.
+{
+     my @arr = @_;
+     my $max = max(@arr);
+     my $offset = length($max);
+     for my $high ( reverse 1 .. $max )
+     {
+
+          my @hist = map {$_ >= $high ? '#' : ' '} @arr;
+          print $high, ' ' x $offset, join(' ', @hist), $/;
+     }
+
+     my @underl = map '_', @arr, $max;
+     print join(' ', @underl), $/;
+     print ' ' x ($offset + 1),  join(' ', @arr)   , $/;
+}
+
+sub estimate_water
+{
+     my @arr = @_;
+
+
+     my @left;
+     my @right;
+     my $volume = 0;
+
+     $left[0] = $arr[0];
+     for my $idx ( 1 .. $#arr )
+     {
+          $left[$idx] = max($left[$idx - 1], $arr[$idx]);
+
+     }
+
+     $right[$#arr] = $arr[$#arr];
+     for my $idx ( reverse 0 .. $#arr - 1 )
+     {
+          $right[$idx] = max($right[$idx + 1], $arr[$idx]);
+     }
+
+
+     for my $idx ( 0 .. $#arr )
+     {
+          $volume += min($left[$idx], $right[$idx]) - $arr[$idx];
+     }
+
+     return $volume;
+}
+
+
+print_histogram(2, 1, 4, 1, 2, 5);
+print estimate_water(2, 1, 4, 1, 2, 5), $/; # 6
+
+print_histogram(3, 1, 3, 1, 1, 5);
+print estimate_water(3, 1, 3, 1, 1, 5), $/; # 6
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