Group Anagrams -- LeetCode

Given an array of strings, group anagrams together.

For example, given: ["eat", "tea", "tan", "ate", "nat", "bat"], 
Return:

[
  ["ate", "eat","tea"],
  ["nat","tan"],
  ["bat"]
]

 

Note:

1. For the return value, each inner list's elements must follow the lexicographic order.
2. All inputs will be in lower-case.

思路：使用哈希表，将每个单词按照其内部字母排序后的结果进行映射。anagram会被映射到同一组中。

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        sort(strs.begin(), strs.end());
        unordered_map<string, vector<string> > dict;
        for (int i = 0, n = strs.size(); i < n; i++)
        {
            string b = strs[i];
            sort(b.begin(), b.end());
            if (dict.count(b)) dict[b].push_back(strs[i]);
            else
            {
                vector<string> tem(1, strs[i]);
                dict.insert(make_pair(b, tem));
            }
        }
        vector<vector<string> > res;
        for (auto i : dict)
            res.push_back(i.second);
        return res;
    }
};