leetcode 49. Group Anagrams (medium)

版权声明：by ruohua3kou https://blog.csdn.net/ruohua3kou/article/details/88963878

对每一个字符串的排序作为哈希表的索引，将字符相同的存到哈希表中对应索引的值中
在discuss中看到一个排序string的函数（限于字符全为小写），加了进来以减少时间复杂度

class Solution
{
  public:
	vector<vector<string>> groupAnagrams(vector<string> &strs)
	{
		unordered_map<string, vector<string>> mapping;
		for (string str : strs)
		{
			mapping[sortstr(str)].push_back(str);
		}
		vector<vector<string>> res;
		for (auto m : mapping)
		{
			res.push_back(m.second);
		}
		return res;
	}
	string sortstr(string str)
	{
		char counter[26] = {0};
		for (char c : str)
		{
			counter[c - 'a']++;
		}
		string res;
		for (int i = 0; i < 26; i++)
		{
			res += string(counter[i], i + 'a');
		}
		return res;
	}
};