algorithms-and-data-structures/Trie.cpp at main · os-moussao/algorithms-and-data-structures · GitHub

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// source: https://gist.github.com/hrsvrdhn/1ae71c25ef1c620c022a544d52df8928
struct Trie {
  map<char,Trie*> children;
  int prefixes;
  bool endofword;
  Trie() {
    prefixes=0;
    endofword=false;
  }
  void insert(string word) {
    Trie *current=this;
    for(int i=0;i<word.size();i++) {
      char ch=word[i];
      Trie *node=current->children[ch];
      if(!node) {
        node=new Trie();
        current->children[word[i]]=node;
      }
      current=node;
      current->prefixes++;
    }
    current->endofword=true;
  }
  bool search(string word) {
    Trie *current=this;
    for(int i=0;i<word.size();i++) {
      char ch=word[i];
      Trie *node=current->children[ch];
      if(!node)
        return false;
      current=node;
    }
    return current->endofword;
  }
  int countPrefix(string word) {
    Trie *current=this;
    for(int i=0;i<word.size();i++) {
      char ch=word[i];
      Trie *node=current->children[ch];
      if(!node) {
        return 0;
      }
      current=node;
    }
    return current->prefixes;
  }
  void erase(string word) {
    if (!search(word)) return;
    Trie *current = this;
    for(int i = 0; i < word.size(); i++) {
      char ch = word[i];
      Trie *node = current->children[ch];
      node->prefixes--;
      if (node->prefixes == 0) {
        current->children.erase(ch);
        delete node;
        return;
      }
      current = node;
    }
    current->endofword = false;
  }
};