49-group-anagrams.cpp

/*
49. Group Anagrams
Medium - 71.6%

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"]]
*/

#include <vector>
#include <string>
#include <unordered_map>
#include <algorithm>
using namespace std;

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, vector<string>> groups;
        
        for (const string& str : strs) {
            // Create a key by sorting the characters
            string key = str;
            sort(key.begin(), key.end());
            
            // Group strings with the same sorted key
            groups[key].push_back(str);
        }
        
        // Extract all groups
        vector<vector<string>> result;
        for (auto& pair : groups) {
            result.push_back(pair.second);
        }
        
        return result;
    }
};