【24】49. Group Anagrams

49. Group Anagrams

• Total Accepted: 114214
• Total Submissions: 354423
• Difficulty: Medium
• Contributors: Admin

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: All inputs will be in lower-case.

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        //哈希表建立的不是对每个字符串来说字母与个数的映射
        //而是所有的字符串排序好后 字符串与其下标list的映射
        /*
        unordered_map<string, vector<int>> m;
        vector<vector<string>> res;
        vector<string> level;
        for(int i = 0; i < strs.size(); i++){
            string s = strs[i];
            sort(s.begin(), s.end());
            m[s].push_back(i);
        }
        
        for(unordered_map<string, vector<int>>::iterator it = m.begin(); it != m.end(); it++){
            if(it -> second.size() > 0){
                for(int i = 0; i < it -> second.size(); i++){
                    level.push_back(strs[it -> second[i]]);
                }
                //res.push_back(level);
            }
            res.push_back(level);
        }
        return res;*/
        
        
        
        unordered_map<string, vector<string>> m;
        vector<vector<string>> res;
        
        for(int i = 0; i < strs.size(); i++){
            string s = strs[i];
            sort(s.begin(), s.end());
            m[s].push_back(strs[i]);
        }
        
        for(auto a : m){
            vector<string> level = a.second;//这里a不是iterator指针 所以他的second用.来读取
            res.push_back(level);
        }
        return res;
    }
};