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run code in 300+ PHP versions simultaneously
<?php $a = ['a' => -1, 'b' => 0.5, 'c' =>0.5]; //Combinations $c = [ ['a','b','c'], ['a','b'], ['a','c'], ['b','c'] ]; foreach($c as $v){ $s = array_sum(array_intersect_key($a,array_flip($v))); echo !$s ? (implode(' & ',$v)) : ''; }
Output for 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.27, 8.4.1 - 8.4.14
a & b & c

preferences:
160.92 ms | 407 KiB | 5 Q