LeetCode49. Group Anagrams

一、题目

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

Example 1:

Input: strs = [“eat”,“tea”,“tan”,“ate”,“nat”,“bat”]
Output: [[“bat”],[“nat”,“tan”],[“ate”,“eat”,“tea”]]
Example 2:

Input: strs = [“”]
Output: [[“”]]
Example 3:

Input: strs = [“a”]
Output: [[“a”]]

Constraints:

1 <= strs.length <= 104
0 <= strs[i].length <= 100
strs[i] consists of lowercase English letters.

二、题解

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        int n = strs.size();
        unordered_map<string,vector<string>> map;
        for(int i = 0;i < n;i++){
            string s = strs[i];
            sort(s.begin(),s.end());
            map[s].emplace_back(strs[i]);
        }
        vector<vector<string>> res;
        //遍历所有的key
        for(auto it = map.begin();it != map.end();it++){
            res.emplace_back(it->second);
        }
        return res;
    }
};