Update 0648-replace-words.cpp

0648-replace-words/0648-replace-words.cpp

@@ -1,43 +1,98 @@
+struct TrieNode {
+ char data;
+ bool isPrefix;
+ TrieNode* children[26];
+};
+
 class Solution {
+private:
+ vector<string> tokenizer(string& line) {
+ vector<string> tokens;
+ stringstream check1(line);
+ string intermediate;
+ while (getline(check1, intermediate, ' ')) {
+ tokens.push_back(intermediate);
+ }
+ return tokens;
+ }
+
 public:
- string replaceWords(vector<string>& dict, string sentence) {
- sort(dict.begin(), dict.end());
- int n = sentence.size();
- string tmp = "";
- string ans = "";
- for (int i = 0 ; i < n ; i++){
- if (sentence[i] == ' '){
- bool flag = false;
- for (auto &s : dict){
- if (s == tmp.substr(0, s.size())){
- ans += s;
- ans += ' ';
- flag = true;
- break;
- }
- }
- if (!flag){
- ans += tmp;
- ans += ' ';
- }
- tmp = "";
- }
- else {
- tmp += sentence[i];
+ TrieNode nodepool[100000]; // Pool of 100K TrieNodes
+ TrieNode* root; // Root of Trie
+ int poolcount; // Always points to next free TrieNode
+
+ void init() {
+ poolcount = 0;
+ root = &nodepool[poolcount++];
+ root->data = '/';
+ root->isPrefix = false;
+ for (int i = 0; i < 26; ++i) {
+ root->children[i] = nullptr;
+ }
+ }
+
+ TrieNode* getNode(char c) {
+ TrieNode* node = &nodepool[poolcount++];
+ node->data = c;
+ node->isPrefix = false;
+ for (int i = 0; i < 26; ++i) {
+ node->children[i] = nullptr;
+ }
+ return node;
+ }
+
+ void insert(string& word) {
+ TrieNode* current = root;
+ for (auto& c : word) {
+ if (current->children[c - 'a'] == nullptr) {
+ current->children[c - 'a'] = getNode(c);
  }
+ current = current->children[c - 'a'];
  }
- bool flag = false;
- for (auto &s : dict){
- if (s == tmp.substr(0, s.size())){
- ans += s;
- ans += ' ';
- flag = true;
+ current->isPrefix = true;
+ }
+
+ bool search(string& prefix) {
+ TrieNode* current = root;
+ for (char& c : prefix) {
+ if (current->children[c - 'a'] == nullptr) {
+ return false;
  }
+ current = current->children[c - 'a'];
+ }
+ return current->isPrefix;
+ }
+
+ string replaceWords(vector<string>& dictionary, string sentence) {
+ init();
+ for (auto& word : dictionary) {
+ insert(word);
  }
- if (!flag){
- ans += tmp;
- ans += ' ';
+
+ string ans = "";
+ vector<string> tokens = tokenizer(sentence);
+
+ for (auto& token : tokens) {
+ bool found = false;
+ string prefix;
+ TrieNode* current = root;
+ for (int i = 1; i <= token.size(); ++i) {
+ string prefix = token.substr(0, i);
+ if (search(prefix)) {
+ ans += prefix;
+ found = true;
+ break;
+ }
+ }
+
+ if (found) {
+ ans += prefix;
+ } else {
+ ans += token;
+ }
+ ans += " ";
  }
+
  return ans.substr(0, ans.size() - 1);
  }
-};
+};