Cassidoo | isIsomorphic String

README.md

Solution to Cassidoo's Week of October 15, 2023 Challenge

Given two strings s and t, determine if they are isomorphic. Two strings are isomorphic if there is a one-to-one mapping possible for every character of the first string to every character of the second string.

My initial version would ignore any non-alphanumeric characters.

That said, this definitely does not handle accents, etc.

isIsomorphic.php

<?php

function isIsomorphic($original, $encrypted) {
	$key = [];

	$original = str_split($original);
	$encrypted = str_split($encrypted);

	if (count($original) != count($encrypted)) {
		// every character MUST exist in both.
		return false;
	}

	for ($i = 0; $i < count($original); $i++) {
		if (!isset($key[$original[$i]])) {
			$key[$original[$i]] = $encrypted[$i];
		}

		if ($key[$original[$i]] != $encrypted[$i]) {
			return false;
		}
	}

	return true;
}

// true
var_dump(isIsomorphic('abb', 'cdd'));
// false
var_dump(isIsomorphic('cassidy', '1234567'));
// true
var_dump(isIsomorphic('cass', '1233'));
// true
var_dump(isIsomorphic('elephant', 'aka0b1td'));
// false
var_dump(isIsomorphic('elephant', 'aka0b1td asd'));
// true
var_dump(isIsomorphic('an elephant', '1t aka0b1td'));
// false
var_dump(isIsomorphic('an elephant', '1taka 0b1td'));
// false
var_dump(isIsomorphic('an elephant', '3t aka0b1td'));