Two strings, a and b, are said to be twins only if they can be made equivalent by performing some number of operations on one or both strings. There are two possible operations: SwapEven: Swap a character at an even-numbered index with a character at another even-numbered index. SwapOdd: Swap a character at an odd-numbered index with a character…

twins.php

function Twins($a, $b) {
  $flag = false;
  $a_len = count($a);
  $b_len = count($b);
	
	if($a_len != $b_len) {
		throw new Exception('array index count mismatched!');
	}
	$result = [];
	for($i = 0; $i<$a_len; $i++) {
		$a_val = $a[$i];
		$b_val = $b[$i];
		$a_val_arr = str_split($a_val);
		$b_val_arr = str_split($b_val);
		
		$flag = false;
		foreach($a_val_arr as $key => $val) {
			$b_key = array_search($val, $b_val_arr);
			if( ($key % 2 == 0 && $b_key % 2 == 0) || ($key % 2 != 0 && $b_key % 2 != 0) ) {
				$flag = true;
			} else if( ($key % 2 == 0 && $b_key % 2 != 0) || ($key % 2 != 0 && $b_key % 2 == 0)) {
				$flag = false;
				break;
			}
		}
		if($flag) {
			$result[$i] = "Yes";
		} else {
			$result[$i] = "No";
		}
		if(count($a_val_arr) != count($b_val_arr)) {
			$result[$i] = "string length mismatched!";
		}
	}
	return $result;
}

$string1 = array("cdab", "dcba");
$string2 = array("abcd", "abcd");
    
$result = Twins($string1, $string2);
echo implode("\n", $result);