Algorithm for matching all elements with another element in the same list, where some have limitations

Question

This array [a, b, c, d, e, f]

I want to match each letter with every other letter except myself, resulting in something like:

• a - c
• b - f
• d - e

The trick is that each letter can be limited by the coincidence of one or more other letters.

So let's say for example

• a cannot be matched with c, d
• c cannot be matched with e, f
• e cannot be matched with

Any directions on how to do this? I use Ruby, but any pseudo-code will be useful.

Thank!

Answer 1

, , - , (, , ). , .

.

Answer 2

, . .

• .
• , , .
• . , , .
• , .

, , , . , , , - .

Answer 3

I'm not sure I understand the problem, but this seems like a question:

%w[a b c d e f].combination(2).to_a - [%w[a c],%w[a d],%w[c e],%w[c f],%w[e a]]
# =>  [["a", "b"], ["a", "e"], ["a", "f"], ["b", "c"], ["b", "d"], ["b", "e"], ["b", "f"], ["c", "d"], ["d", "e"], ["d", "f"], ["e", "f"]]

Answer 4

$letters = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j');
$exclusions = array('a' => array('e', 'd', 'c'), 'b' => array('a','b', 'c','d')); foreach ($letters as $matching) {
foreach ($letters as $search) {
if(!in_array($search,$exclusions[$matching])){
if($search!=$matching){
$match[$matching][] = $search;
}
}
}
}
print_r ($ match);

The innermost EVAL can be added to the next outer ...

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