Merge pull request #12952 from wanderdoc/master

pwc 345 (wanderdoc)

2 files changed, 172 insertions, 0 deletions

diff --git a/challenge-345/wanderdoc/perl/ch-1.pl b/challenge-345/wanderdoc/perl/ch-1.pl
new file mode 100644
index 0000000000..71c5ba0db0
--- /dev/null
+++ b/challenge-345/wanderdoc/perl/ch-1.pl
@@ -0,0 +1,68 @@
+#!perl
+use strict;
+use warnings FATAL => qw(all);
+
+=prompt
+You are given an array of integers, @ints.
+Find all the peaks in the array, a peak is an element that is strictly greater than its left and right neighbours. Return the indices of all such peak positions.
+
+Example 1
+
+Input: @ints = (1, 3, 2)
+Output: (1)
+
+
+Example 2
+
+Input: @ints = (2, 4, 6, 5, 3)
+Output: (2)
+
+
+Example 3
+
+Input: @ints = (1, 2, 3, 2, 4, 1)
+Output: (2, 4)
+
+
+Example 4
+
+Input: @ints = (5, 3, 1)
+Output: (0)
+
+
+Example 5
+
+Input: @ints = (1, 5, 1, 5, 1, 5, 1)
+Output: (1, 3, 5)
+
+=cut
+
+
+use Test2::V0 -no_srand => 1;
+
+is([peak_positions(1, 3, 2)], [1], 'Example 1');
+is([peak_positions(2, 4, 6, 5, 3)], [2], 'Example 2');
+is([peak_positions(1, 2, 3, 2, 4, 1)], [2, 4], 'Example 3');
+is([peak_positions(5, 3, 1)], [0], 'Example 4');
+is([peak_positions(1, 5, 1, 5, 1, 5, 1)], [1, 3, 5], 'Example 5');
+done_testing();
+
+sub peak_positions
+{
+     my @arr = @_;
+     if ( scalar(@arr) == 1) { return 0; } 
+     my @positions;
+     for my $idx ( 0 .. $#arr )
+     {
+          if ( 
+               ($idx == 0 and $arr[$idx] > $arr[$idx+1]) or 
+               ($idx < $#arr  and $arr[$idx] > $arr[$idx-1] 
+                              and $arr[$idx] > $arr[$idx+1]) or
+               ($idx == $#arr and $arr[$idx] > $arr[$idx-1])
+          )
+          {
+               push @positions, $idx;
+          }
+     }
+     return @positions;
+}
diff --git a/challenge-345/wanderdoc/perl/ch-2.pl b/challenge-345/wanderdoc/perl/ch-2.pl
new file mode 100644
index 0000000000..105b4df56e
--- /dev/null
+++ b/challenge-345/wanderdoc/perl/ch-2.pl
@@ -0,0 +1,104 @@
+#!perl
+use strict;
+use warnings FATAL => qw(all);
+
+=prompt
+You are given an integer array @ints where each element is either a positive integer or -1.
+We process the array from left to right while maintaining two lists:
+
+@seen: stores previously seen positive integers (newest at the front)
+@ans: stores the answers for each -1
+
+Rules:
+
+If $ints[i] is a positive number -> insert it at the front of @seen
+If $ints[i] is -1:
+
+Let $x be how many -1s in a row we’ve seen before this one.
+
+If $x < len(@seen) -> append seen[x] to @ans
+
+Else -> append -1 to @ans
+
+At the end, return @ans.
+
+Example 1
+
+Input: @ints = (5, -1, -1)
+Output: (5, -1)
+
+@seen = (5)
+First  -1: @ans = (5)
+Second -1: @ans = (5, -1)
+
+
+Example 2
+
+Input: @ints = (3, 7, -1, -1, -1)
+Output: (7, 3, -1)
+
+@seen = (3, 7)
+First  -1: @ans = (7)
+Second -1: @ans = (7, 3)
+Third  -1: @ans = (7, 3, -1)
+
+
+Example 3
+
+Input: @ints = (2, -1, 4, -1, -1)
+Output: (2, 4, 2)
+
+
+Example 4
+
+Input: @ints = (10, 20, -1, 30, -1, -1)
+Output: (20, 30, 20)
+
+
+Example 5
+
+Input: @ints = (-1, -1, 5, -1)
+Output: (-1, -1, 5)
+
+=cut
+
+use Test2::V0 -no_srand => 1;
+
+
+
+is([last_visitor(5, -1, -1)], [5, -1], 'Example 1');
+is([last_visitor(3, 7, -1, -1, -1)], [7, 3, -1], 'Example 2');
+is([last_visitor(2, -1, 4, -1, -1)], [2, 4, 2], 'Example 3');
+is([last_visitor(10, 20, -1, 30, -1, -1)], [20, 30, 20], 'Example 4');
+is([last_visitor(-1, -1, 5, -1)], [-1, -1, 5], 'Example 5');
+done_testing();
+
+sub last_visitor
+{
+     my @arr = @_;
+     my (@seen, @ans);
+     my $prev_int;
+     my $x = 0;
+     for my $int ( @arr )
+     {
+          if ( $int > 0 )
+          {
+               unshift @seen, $int;
+               $x = 0;
+          }
+          elsif ( $int == -1 )
+          {
+               push @ans, $x < scalar(@seen) ? $seen[$x] : $int;
+               if ( defined($prev_int) and $prev_int == -1 )
+               {
+                    $x++;
+               }
+               else
+               {
+                    $x = 1;
+               }
+          }
+          $prev_int = $int;
+     }
+     return @ans;
+}