uni.php

$words = ['кит', 'кот', 'тик', 'кти', 'ток', 'ков'];

$hash = [];

foreach($words as $word) {
	$lowerWord = strtolower($word);
	$wordArray = preg_split('//u', $lowerWord, null, PREG_SPLIT_NO_EMPTY);
	sort($wordArray);
	$sorted = implode('',$wordArray);
	
	if (!isset($hash[$sorted])) {
		$hash[$sorted] = [];
	}
	$hash[$sorted][] = $word;
}


$return = max($hash);
if (count($return) == 1) {
	$return = [];
}

print_r($return);


$result = [];
$direction = 1;
$step = 1;
$n = 3;
while($step <= $n) {
	if ($step % 2) {
		$direction = 1;
		$from = 1;
		$to = $step;
	} else {
		$direction = -1;
		$from = $step;
		$to = 1;		
	}
	
	$range = range($from, $to, $direction);
	$result[] = implode('-', $range);
	$step++;
}

print_r($result);



$arr = [1, 5, 3, 4, 2, 2]; $k=3;

sort($arr);
$sortedArr = array_flip($arr);
print_r($sortedArr);
$pairs = [];
$uniquePairs = 0;

foreach($sortedArr as $number => $value) {
	if (isset($sortedArr[$number + $k])) {
		$uniquePairs++;
	}
}

print_r($uniquePairs);