如何在阵列中分别选择2个项目，确保每个集合都已输出

Question

Lets say I have an array of numbers: [1,2,3].

How can I loop through this array to create an array of possible permutations.

I'm expecting outputs like: [1,2], [1,3], [2,1], [2,3], [3,1], [3,2].

Answer 1

• Simple nested loops required for the same input array

Do the following:

$input = array(1,2,3);

$output = array();

// to get all possible permutations
// for first value in the permutation, loop over all array values
foreach ($input as $value1) {

    // for second value in the permutation, loop again similarly
    foreach ($input as $value2) {

        if ($value1 !== $value2)  // dont consider same values
            $output[] = array($value1, $value2);
    }
}