<?php 
 
namespace Fuse\Search\Bitap; 
 
function createPatternAlphabet(string $pattern): array 
{ 
    $mask = []; 
 
    for ($i = 0, $len = mb_strlen($pattern); $i < $len; $i += 1) { 
        $char = mb_substr($pattern, $i, 1); 
        $mask[$char] = ($mask[$char] ?? 0) | (1 << $len - $i - 1); 
    } 
 
    return $mask; 
} 
 
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