Anagrams

• Time : $O(nlogn)$
• Space : $O(n)$

vector<vector<int>> Solution::anagrams(const vector<string> &A) {
    unordered_map<string, vector<int>> mp;
    for(int i = 0; i < A.size(); i++) {
        string s = A[i];
        sort(begin(s), end(s));
        mp[s].push_back(i+1);
    }
    vector<vector<int>> res;
    for(auto [_,v] : mp) res.push_back(v);
    sort(begin(res), end(res));
    return res;
}