With the power of Perlmonks::Combinatorics I combined Lanx's solution and mine: 

sub Eily_LanX {
    my ($length, $ones) = @_;
    my $iter = combinations([0..$length-1], $ones);
    my (@r, $str);
    while (my $positions = $iter->next) {
        $str = '0' x $length;
        substr $str, $_, 1, '1' for @$positions;
        push @r, $str;
    }
    return \@r
}

[download]
              Rate salva tybalt89_re choroba tybalt89 Eily GrandFather
+ Eily_LanX
salva        795/s    --        -10%    -57%     -59% -62%        -84%
+      -85%
tybalt89_re  879/s   11%          --    -52%     -54% -59%        -82%
+      -83%
choroba     1842/s  132%        110%      --      -4% -13%        -63%
+      -64%
tybalt89    1916/s  141%        118%      4%       -- -10%        -61%
+      -63%
Eily        2120/s  167%        141%     15%      11%   --        -57%
+      -59%
GrandFather 4960/s  524%        464%    169%     159% 134%          --
+       -4%
Eily_LanX   5154/s  548%        486%    180%     169% 143%          4%
+        --

[download]

In reply to Re^2: Generate all unique combinations of 1 and 0 using specified length of "0"-string and count of 1's by Eily
in thread Generate all unique combinations of 1 and 0 using specified length of "0"-string and count of 1's by Lana

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