LeetCode-in-All

49. Group Anagrams

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 <= 104
• 0 <= strs[i].length <= 100
• strs[i] consists of lowercase English letters.

Solution

class Solution {
  List<List<String>> groupAnagrams(List<String> strs) {
    Map<String, List<String>> m = {};

    if (strs.length == 1) return [strs];
    else if (strs.length == 0) return [[""]];
    else {
      for (String s in strs) {
        List<String> charList = s.split('');
        charList.sort();
        String sortedS = charList.join();

        if (m[sortedS] == null) {
          m[sortedS] = [s];
        } else {
          m[sortedS]?.add(s);
        }
      }
      return m.values.toList();
    }
  }
}

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