Get Distinct Elements Common To All Rows of n x n Matrix having unique values

getDistinctElementsCommonToAllRows.php

<?php

function getDistinctElementsCommonToAllRows($matrix) {
	$matches = '';
	$matrixLength = count($matrix);
	$matrixLastIndex = $matrixLength - 1;
	$matrixPivotIndex = round($matrixLastIndex / 2);
	for ($i=0; $i < $matrixPivotIndex; $i++) { 
		$row = $matrix[$i];
		$anotherRow = $matrix[$matrixLastIndex - $i];
		$currentRowMatch = '';
		// @todo improve complexity by refactoring below 2 nested loops
		foreach ($row as $key => $rowValue) {
			foreach ($anotherRow as $key => $anotherRowValue) {
				// var_dump("$rowValue === $anotherRowValue => " . ($isMatching ? 'true' : 'false'));
				$isMatching = $rowValue === $anotherRowValue;
				if ($isMatching) {
					if ($currentRowMatch) $currentRowMatch .= ' ';
					$currentRowMatch .= $rowValue;
				}
			}
		}
		if (!$currentRowMatch) break;
		if ($matches && $matches !== $currentRowMatch) break;
		$matches = $currentRowMatch;
	}
	return $matches ?: 'No match found';
};

$sampleMatrix = [
	[2, 1, 4, 3],
	[1, 2, 3, 2],
	[3, 6, 2, 3],
	[5, 2, 5, 3]
];
// echo getDistinctElementsCommonToAllRows($sampleMatrix);
// Output: 2 3

$sampleMatrix2 = [
	[12, 1, 14, 3, 16],
	[14, 2, 1, 3, 35],
	[14, 1, 14, 3, 11],
	[14, 25, 3, 2, 1],
	[1, 18, 3, 21, 14]
];
echo getDistinctElementsCommonToAllRows($sampleMatrix2);
// Output: 1 3 14