171. Anagrams【medium】

Given an array of strings, return all groups of strings that are anagrams.

Notice

All inputs will be in lower-case

 

Example

Given ["lint", "intl", "inlt", "code"], return ["lint", "inlt", "intl"].

Given ["ab", "ba", "cd", "dc", "e"], return ["ab", "ba", "cd", "dc"].

Challenge

What is Anagram?
- Two strings are anagram if they can be the same after change the order of characters.

解法一：

 class Solution {
 public:
     /**
      * @param strs: A list of strings
      * @return: A list of strings
      */
     string getSortedString(string &str) {
         static int count[];
         for (int i = ; i < ; i++) {
             count[i] = ;
         }
         for (int i = ; i < str.length(); i++) {
             count[str[i] - 'a']++;
         }

         string sorted_str = "";
         for (int i = ; i < ; i++) {
             for (int j = ; j < count[i]; j++) {
                 sorted_str = sorted_str + (char)('a' + i);
             }
         }
         return sorted_str;
     }

     vector<string> anagrams(vector<string> &strs) {
         unordered_map<string, int> hash;

         for (int i = ; i < strs.size(); i++) {
             string str = getSortedString(strs[i]);
             if (hash.find(str) == hash.end()) {
                 hash[str] = ;
             } else {
                 hash[str] = hash[str] + ;
             }
         }

         vector<string> result;
         for (int i = ; i < strs.size(); i++) {
             string str = getSortedString(strs[i]);
             if (hash.find(str) == hash.end()) {
                 continue;
             } else {
                 if (hash[str] > ) {
                     result.push_back(strs[i]);
                 }
             }
         }
         return result;
     }
 };

手动实现了字符串的排序，有些复杂，参考@NineChapter 的代码

解法二：

 class Solution {
 public:
     /**
      * @param strs: A list of strings
      * @return: A list of strings
      */
     vector<string> anagrams(vector<string> &strs) {
         int size = strs.size(), i = ;
         if (size <= ) {
             return vector<string>();
         }

         vector<string> result;
         map<string, int> hash;
         for (i = ; i < size; i++) {
             string temp = strs[i];
             sort(temp.begin(), temp.end());
             hash[temp]++;
         }
         for (i = ; i < size; i++) {
             string temp = strs[i];
             sort(temp.begin(), temp.end());
             if (hash[temp] > ) {
                 result.push_back(strs[i]);
             }
         }
         return result;
     }
 };

直接用STL的sort函数搞