LeetCode-49. Group Anagrams

Description

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.

Solution 1(C++)

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, multiset<string>> mp;
        for (string s : strs) {
            string t = s; 
            sort(t.begin(), t.end());
            mp[t].insert(s);
        }
        vector<vector<string>> anagrams;
        for (auto m : mp) { 
            vector<string> anagram(m.second.begin(), m.second.end());
            anagrams.push_back(anagram);
        }
        return anagrams;
    }
};

Solution 2(C++)

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map <string, vector<string>> hashmap;
        for(int  i = 0 ; i<strs.size(); i++){
            string key = strs[i];
            sort(strs[i].begin(), strs[i].end());
            hashmap[strs[i]].push_back(key);
        }
        vector<vector<string>> solution;
        unordered_map<string, vector<string>> :: iterator  i ; 
        for(i = hashmap.begin() ; i!=hashmap.end(); i++){
            solution.push_back(i->second) ;
        }
        return solution;
    }
};

算法分析

算法没啥好多多说的，主要是STL主要数据结构要熟练使用。

程序分析

请复习：

• C++——std::Set
• C++——std::Map
• C++——std::Vector