Question

How to count the total of all pairs permutations in an array with PHP

Answer 1

$arr1 = array(1, 8, 5);

// The pairs are: (1, 8), (1, 5), (8, 1), (8, 5), (5, 1), (5, 8)

$total_pairs = count($arr1) * (count($arr1) - 1);
echo "Total Pairs = " . $total_pairs . "\n";

$arr2 = array(1, 8, 5, 2);

// The pairs are: (1, 8), (1, 5), (1, 2), (8, 1), (8, 5), (8, 2),
//                (5, 1), (5, 8), (5, 2), (2, 1), (2, 8), (2, 5)

$total_pairs = count($arr2) * (count($arr2) - 1);
echo "Total Pairs = " . $total_pairs . "\n";



/*
run:

Total Pairs = 6
Total Pairs = 12

*/

 

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