The trick is you can connect to x1, y1 or to x2, y2. Depending on which one you choose, you also have to push the right coordinates to the resulting array: 
#!/usr/bin/perl
use warnings;
use strict;

my @AoA = (
    [11,29, 10,25],
    [15,35, 11,29],
    [15,15, 11,21],
    [10,25, 11,21],
    [15,35, 21,39],
    [25,40, 21,39],
    [21,11, 25,10],
    [15,15, 21,11],
    [35,35, 29,39],
    [29,39, 25,40],
    [35,15, 29,11],
    [25,10, 29,11],
    [40,25, 39,29],
    [35,35, 39,29],
    [39,21, 40,25],
    [35,15, 39,21],
);

my @line = @{ shift @AoA };
while (@AoA) {
    my ($index) = grep {
            $AoA[$_][0] == $line[-2] && $AoA[$_][1] == $line[-1]
         or $AoA[$_][2] == $line[-2] && $AoA[$_][3] == $line[-1]
      } 0 .. $#AoA;
    if (defined $index) {
        my $new = splice @AoA, $index, 1;
        my $first = $new->[0] == $line[-2] ? 2 : 0;
        push @line, @{ $new }[$first, $first + 1];
    } else {
        die "No solution for @line[-2, -1]. (@line)\n";
    }
}

print "@line\n";

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لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re: Combine line segments to form a single line by choroba
in thread Combine line segments to form a single line by bangor

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