648. Replace Words（LeetCode）

In English, we have a concept called root, which can be followed by some other words to form another longer word - let's call this word successor. For example, the root an, followed by other, which can form another word another.

Now, given a dictionary consisting of many roots and a sentence. You need to replace all the successor in the sentence with theroot forming it. If a successor has many roots can form it, replace it with the root with the shortest length.

You need to output the sentence after the replacement.

Example 1:

Input: dict = ["cat", "bat", "rat"]
sentence = "the cattle was rattled by the battery"
Output: "the cat was rat by the bat"

Note:

1. The input will only have lower-case letters.
2. 1 <= dict words number <= 1000
3. 1 <= sentence words number <= 1000
4. 1 <= root length <= 100
5. 1 <= sentence words length <= 1000

   class Solution {
   public:
       string replaceWords(vector<string>& dict, string sentence) {
           if (sentence.size() == 0 || dict.size() == 0)
               return sentence;
           stringstream ss(sentence);
           vector<string> vet;
           string str;
           while (ss >> str)
           {
               vet.push_back(str);
           }
           for (int i = 0; i < vet.size(); i++)
           {
               for (int j = 0; j < dict.size(); j++)
               {
                   /*cout << vet[i] << vet[i].size() << " " << dict[j] << dict[j].size() << "  22" << vet[i].substr(0, dict[j].size()) << endl;*/
   
                   if (vet[i].size() >= dict[j].size() && vet[i].substr(0, dict[j].size()) == dict[j])
                   {
                               vet[i] = dict[j];    
                               /*cout <<"11111111"<< vet[i] << endl;*/
                   }
               }
           }
           string str1 = "";
           for (int i = 0; i < vet.size(); i++)
           {
               str1 += vet[i];
               if (i != vet.size()-1)
               str1 += " ";
   
           }
           return str1;
       }
   };

   别人用字典树做的如下：

   class Solution {
   private:
       class TrieNode{
           public:
           bool eow;
           vector<TrieNode*> chars;
           TrieNode():eow(false), chars(vector<TrieNode*>(26,NULL)){
               
           }
       };
       
       class Trie{
           public:
           TrieNode* head;
           
           Trie():head(new TrieNode()) {}
           
           bool isWord(string str){
              TrieNode* cur = head;
               for (int i = 0; i < str.size(); i++){
                   char c = str[i];
                   int index = (c-'a') %26;
                   if (cur->chars[index] == NULL){
                       return false;
                   }
                   cur = cur->chars[index];
                   if (index == str.size() - 1){
                       return cur->eow;
                   }
               }
           }
           
           void insertWord(string str){
               TrieNode* cur = head;
               for (int i = 0; i < str.size(); i++){
                   char c = str[i];
                   int index = (c-'a') %26;
                   if (cur->chars[index] == NULL){
                       cur->chars[index] = new TrieNode();
                   }
                   cur = cur->chars[index];
                   if (i == str.size() - 1){
                       cur->eow = true;
                   }
               }
           }
           
           string getShortestPrefix(string str){
               TrieNode* cur = head;
               for (int i = 0; i < str.size(); i++){
                   char c = str[i];
                   int index = (c-'a') %26;
                   if (cur->chars[index] == NULL){
                       return str;
                   }
                   if (cur->chars[index]->eow){
                       return str.substr(0,i+1);
                   }
                   cur = cur->chars[index];
               }
               return str;
           }
       };
   public:
       string replaceWords(vector<string>& dict, string sentence) {
           Trie trie;
           for (string str : dict){
               trie.insertWord(str);
           }
           
           string ans = "";
           int index = 0, beg = 0;   
           while ((index = sentence.find(' ',beg)) != string::npos){
               ans += trie.getShortestPrefix(sentence.substr(beg, index - beg)) + " ";
               beg = index + 1;
           }
           ans += trie.getShortestPrefix(sentence.substr(beg));
           return ans;
       }
   };