49. Group Anagrams

Posted 2021-01-04 ruisha

---

Given an array of strings, group anagrams together.

Example:

Input: ["eat", "tea", "tan", "ate", "nat", "bat"],
Output:
[
  ["ate","eat","tea"],
  ["nat","tan"],
  ["bat"]
]

Note:

• All inputs will be in lowercase.
• The order of your output does not matter.

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题目要求把anagrams放在一起，可以考虑用hash table。对于hash table来讲，需要考虑key是什么：anagram排序后的字符串可以当作key

sort a string: 

sort(s.begin(),s.end());

　　

 1 class Solution {
 2 public:
 3     vector<vector<string>> groupAnagrams(vector<string>& strs) {
 4         unordered_map<string,vector<string>> map; //key:sorted string, value: vector of strings with the same key
 5         for(auto s: strs){
 6             string tmp = s;
 7             sort(tmp.begin(),tmp.end());
 8             map[tmp].push_back(s);
 9         }
10         
11         vector<vector<string>> result;
12         for(auto it: map){
13             result.push_back(it.second);
14         }
15         
16         return result;
17     }
18 };