49.Group Anagrams

 

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.

    我们可以利用map来解决这个问题。map的key设置为排序后的字符串，value为字符串数组，将每一个排序之后的值为key的字符串加入value这个数组。对于每一个字符串s，复制一个副本str，将str排序后，将s加入map[str]中。然后依次遍历map，将value对应的数组排序之后加入将要返回的result数组中。最后返回result即可。

1. class Solution {
   public:
       vector<vector<string>> groupAnagrams(vector<string>& strs) {
           unordered_map<string,vector<string>> map;
           for(auto &s: strs){
               string str(s);
               sort(str.begin(),str.end());
               map[str].push_back(s);
           }
           vector<vector<string>> result(map.size());
           int i=0;
           for(auto it=map.begin();it!=map.end();it++,i++){
               result[i].swap(it->second);
               sort(result[i].begin(),result[i].end());
           }
           return result;
           
       }
   };