Maximal outline of a gap competition

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Many thanks to
Bob Henderson (USA)
for entering this
problem.

Start with a set of pentominoes :

Look for a shape containing all pentominoes once, where every pentomino must border at least one other. In our example there is a hole, of which the outline has a total length of 74 units (the red line).

Try to find a solution with a maximal outline.

When the outlines form two solutions have the same length, the one with the smallest area wins.

For solving the problem Exel can be used. We have a file containing the pentominoes.