Leetcode PHP题解--D63 917. Reverse Only Letters

<?php

class Solution {

​

    /**

     * @param String $S

     * @return String

     */

    function reverseOnlyLetters($S) {

        $S = str_split($S);

        $chars = [];

        $others = [];

        foreach($S as $key=>$char){

            if(($char>='a' && $char<='z')

              || ($char>='A' && $char<='Z')

            ){

                $chars[$key] = $char;

            }

            else{

                $others[$key] = $char;

            }

        }

        $keys = array_keys($chars);

        $chars = array_reverse($chars);

        $chars = array_combine($keys,$chars);

        $S = $chars+$others;

        ksort($S);

        return implode('',$S);

    }

}