49. Group Anagrams

Problem Statement

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.

C++

Source file

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, int> m;
        vector<vector<string>> v;
        int i=0;
        for(auto s:strs){
            string K = s;
            sort(K.begin(),K.end());
            if(!m[K])
                m[K]=++i, v.push_back({s});
            else v[m[K]-1].push_back(s);
        }
        return v;
    }
};