max_occuring_alphanumeric_character_in_string.php

<?php
/**
 * Author: git@ashbeats
 * Date: 6/12/2019
 * Time: 10:46 PM
 */

$testCases = [
    '123Adggaaabaaaaaaabbc'                                => 'a',
    'aaabbb'                                               => 'a', // a
    'baaabbb'                                              => 'b', // b
    'baaa1111111111bbb'                                    => '1', // 1
    'baaa1111111111bbb-----------------'                   => '1', // 1
    'baa##a11111111^^11bbb'                                => '1', // 1
    'baa##a1111       1111^^11bbb'                         => '1', // 1
    'ជុន ចាន់បុត្រ apple អ្នកវិភាគដ៏ឆ្នើម ដែលគួរចង់ស្ដាប់' => 'p',  // p
];

/**
 * Simple way to solve it.
 *
 * @param $string
 *
 * @return mixed
 */
function method_1(string $string): string
{
    preg_match_all( '/[a-zA-Z0-9]/i', $string, $results, PREG_PATTERN_ORDER );
    $counts = array_count_values( $results[ 0 ] );
    $max = 0;
    foreach ( $counts as $char => $seen ) {
        $max = ( $seen > $max ) ? $seen : $max;
    }

    return array_search( $max, $counts, true );
}

/***
 * This is the shortest version for now in php...
 *
 * @param $string
 *
 * @return mixed
 */
function method_2(string $string): string
{
    preg_match_all( '/[a-zA-Z0-9]/i', $string, $results, PREG_PATTERN_ORDER );
    $counts = array_count_values( $results[ 0 ] );

    return array_search(
        max( array_values( $counts ) ),
        $counts,
        true
    );
}

/******
 *  Run the tests below.
 */
$passed = true;
foreach ( $testCases as $seed => $expected ) {

    $a = method_1( $seed );
    $b = method_2( $seed );

    if ( $a !== $b ) {
        echo "Both methods yielded different results. Hmm... \n";
    }

    if ( $a !== $expected ) {
        $passed = false;
        echo " ✘ Failed for seed: $seed\n";
        echo "\t - Expected was: $expected\n";
        echo "method_1 failed. Returned ($a) \n";
        break;
    }
    if ( $b !== $expected ) {
        $passed = false;
        echo " ✘ Failed for seed: $seed\n";
        echo "\t - Expected was: $expected\n";
        echo "method_2 failed. Returned ($b) \n";
        break;
    }
}


if ( $passed ) {
    echo "\n ✔ All tests passed!\n\n";
}