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#+TITLE: Challenge 078

* Task 1 - Leader Element
You are given an array @A containing distinct integers.

Write a script to find all leader elements in the array @A. Print (0) if
none found.

- An element is leader if it is greater than all the elements to its
  right side.
** Perl
- Program: [[file:perl/ch-1.pl]]

We take input from =@ARGV=, loop over it. And then we loop over the
elements at right, goto next if =$arg= is less than =$elm=. This will push
all the leader elements to =@leader=.
#+BEGIN_SRC perl
my @leader;
MAIN: while (my $arg = shift @ARGV) {
    foreach my $elm (@ARGV) {
        next MAIN if $arg < $elm;
    }
    push @leader, $arg;
}
#+END_SRC
* Task 2 - Left Rotation
You are given array @A containing positive numbers and @B containing one
or more indices from the array @A.

Write a script to left rotate @A so that the number at the first index
of @B becomes the first element in the array. Similary, left rotate @A
again so that the number at the second index of @B becomes the first
element in the array.
** Perl
- Program: [[file:perl/ch-2.pl]]

Loop over =@B= & then rotate the elements. Same could've been done with
Left Rotation, I find this easier to understand.
#+BEGIN_SRC perl
my @A = qw(10 20 30 40 50);
my @B = qw(3 4);

foreach (@B) {
    my @tmp = @A;
    foreach (1 ... scalar @tmp - $_) {
        unshift @tmp, pop @tmp;
    }
    print join(', ', @tmp), "\n";
}
#+END_SRC