Per OP Update: I have an array Say, @array1 = qw (1,1,1,2,3,4,4,4,5,6,1,1,1,1,...). From this array i have to extract an output as "1,1,1,2,3,4,4,4,5,6,1" (i.e. to remove the X-number of 1's with just 1).

One way:

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my @ra = (1, 1, 1, 2, 3, 4, 4, 4, 5, 6, 1, 1, 1);
 dd \@ra;
 ;;
 my $one;
 $one = pop @ra while $ra[-1] == 1;
 push @ra, $one if defined $one;
 dd \@ra;
"
[1, 1, 1 .. 4, 4, 4, 5, 6, 1, 1, 1]

[1, 1, 1 .. 4, 4, 4, 5, 6, 1]
[download]

Update: Another way:

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my @ra = (1, 1, 1, 2, 3, 4, 4, 4, 5, 6, 1, 1, 1);
 dd \@ra;
 ;;
 my $highest;
 for my $i (reverse 0 .. $#ra) {
   last if $ra[$i] != 1;
   $highest = $i;
   }
 $#ra = $highest if defined $highest;
 dd \@ra;
"
[1, 1, 1 .. 4, 4, 4, 5, 6, 1, 1, 1]

[1, 1, 1 .. 4, 4, 4, 5, 6, 1]
[download]

Upon reflection, I think the second approach is better: it's more flexible. If one wanted to trim all but one undef value from the end of an array, one need only change the test within the for-loop from
    last if $ra[$i] != 1;
to
    last if defined $ra[$i];
and the job's done. The first approach does not have this flexibility.

My Sincere apologies, Series can be in any order. Not necessarily ascending, can be any random number in-between the 1's. Between the value '5' & '6', as demonstrated below, there will not be any 1's either. Say: my @array1 = (1,1,1,5,3,4,4,4,2,6,1,1,1,1,1); Expected output:(1,1,1,5,3,4,4,4,2,6) or (1,1,1,5,3,4,4,4,2,6,1) : getting anyone of it is fine.

You've been given solutions that will give you either of these outputs. Take your pick.

---

Give a man a fish:  <%-(-(-(-<

I have an array Say, #array1 = qw (1,1,1,2,3,4,4,4,5,6,1,1,1). From this array i have to extract an output as "1,1,1,2,3,4,4,4,5,6" (i.e. to remove the number of 1's from the end alone).

But that's not the same thing as finding unique values...?

If you have an array, say my @array1 = (1,1,1,2,3,4,4,4,5,6,1,1,1);, one way to remove the 1's from the end is like this: pop @array1 while $array1[-1]==1;, but that might be inefficient if you have a large number of 1's at the end of the array.

For help with your code, please make it more readable by adding <code> tags.

Dear AM, I have modified the query accordingly. Kindly do help me out. Yes, it has nothing to do with unique. Was trying a different step, kindly ignore the same.

Please see How do I change/delete my post?, in particular "It is uncool to update a node in a way that renders replies confusing or meaningless".

Why do you need the repeated 1's removed? If the last number repeated is something other than a 1, should it be pruned too? Some of the solutions you've been given could be easily modified to allow for that.