Medium
Given an array of strings strs, group the anagrams together. You can return the answer in any order.
An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.
Example 1:
Input: strs = [“eat”,”tea”,”tan”,”ate”,”nat”,”bat”]
Output: [[“bat”],[“nat”,”tan”],[“ate”,”eat”,”tea”]]
Example 2:
Input: strs = [””]
Output: [[””]]
Example 3:
Input: strs = [“a”]
Output: [[“a”]]
Constraints:
1 <= strs.length <= 1040 <= strs[i].length <= 100strs[i] consists of lowercase English letters.class Solution {
    /**
     * @param String[] $strs
     * @return String[][]
     */
    public function groupAnagrams($strs) {
        $hm = array();
        foreach ($strs as $s) {
            $ch = str_split($s);
            sort($ch);
            $temp = implode($ch);
            if (!array_key_exists($temp, $hm)) {
                $hm[$temp] = array();
            }
            array_push($hm[$temp], $s);
        }
        return array_values($hm);
    }
}