$ cat spw759180_NetWallah 
#!/usr/bin/perl
#
use strict;
use warnings;

my @probs =(0,0.1,0.53,0.51,0.59,0.67,0.2,0.04,0.05,0.56,0.89,0.75,0.6);
my $t;
print $_ . (",","\n")[$t=1-$t]  
    for  grep {($probs[$_] >=.5 .. $probs[$_]> .5) and $t=!$t }
           0..$#probs
$ ./spw759180_NetWallah
2
4,9
11,$

##</code><code>##

use strict;
use warnings;

my @probs = (
   0,
   0.1,
   0.53,
   0.51,
   0.59,
   0.67,
   0.2,
   0.04,
   0.05,
   0.56,
   0.89,
   0.75,
   0.1,
   0.51,
   0.6,
   0.2,
   0.7,
   );

my @inRange =
   grep { $probs[ $_ ] > 0.5 .. $probs[ $_ ] > 0.5 }
   0 .. $#probs;

my @starts =
   map  { $inRange[ $_ ] }
   grep {
            $_ == 0
            ||
            $inRange[ $_ ] - $inRange[ $_ - 1 ] != 1
        }
   0 .. $#inRange;

my @ends =
   map  { $inRange[ $_ ] }
   grep {
            $_ == $#inRange
            ||
            $inRange[ $_ + 1 ] - $inRange[ $_ ] != 1
        }
   0 .. $#inRange;

printf qq{%3d%3d\n}, $starts[ $_ ], $ends[ $_ ] for 0 .. $#starts;

##</code><code>##

  2  5
  9 11
 13 14
 16 16