字母异位词分组

 1 class Solution {
 2 public:
 3     vector<vector<string>> groupAnagrams(vector<string>& strs) {
 4         vector<vector<string>> ans; //返回的参数
 5         unordered_map<int, int> mem; //hash表
 6         int size = 0;
 7         for(auto str: strs){
 8             int sum = 0;
 9             for(auto ch:str){
10                 int index = hashgenerate(ch);
11                 sum += index;
12             }
13             if(!mem.count(sum)){
14                 vector<string> temp;
15                 temp.push_back(str);
16                 ans.push_back(temp);
17                 mem[sum] = size++;
18             }
19             else{
20                 int index = mem[sum];
21                 ans[index].push_back(str);
22             }
23         }
24         return ans;
25     }
26     //构建的Hash映射表
27     int hashgenerate(char ch){
28         int i = ch;
29         return  ( 5 *i*i*i/26 + i*371 - i*i*997 + 99);
30     }
31 };