LeetCode-49. Group Anagrams

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.

题解：

直接对字符串排序，建立索引

class Solution {
public:
  vector<vector<string>> groupAnagrams(vector<string>& strs) {
    vector<vector<string>> res;
    int n = strs.size();
    if (n == 0) {
      return res;
    }
    vector<string> data(strs);
    map<string, int> m;
    int k = 0;
    for (int i = 0; i < n; i++) {
      sort(data[i].begin(), data[i].end());
      if (m.find(data[i]) == m.end()) {
        m.insert(make_pair(data[i], k));
        vector<string> idx;
        idx.push_back(strs[i]);
        res.push_back(idx);
        k++;
      }
      else {
        res[m[data[i]]].push_back(strs[i]);
      }
    }
    return res;
  }
};