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December 18, 2018 04:00
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Simple Trie implementation in C++
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| #include <iostream> | |
| #include <map> | |
| #include <memory> | |
| #include <string> | |
| #include <vector> | |
| #include <cassert> | |
| using namespace std; | |
| struct Node { | |
| constexpr static char End = '\0'; | |
| Node (const char _c) | |
| : c{_c}, childs{} | |
| {} | |
| char c; | |
| map<char, unique_ptr<Node>> childs; | |
| }; | |
| void insert(string::const_iterator begin, string::const_iterator end, Node& h) { | |
| if (begin == end) | |
| h.childs.emplace(Node::End, nullptr); | |
| else { | |
| auto p = h.childs.emplace(*begin, make_unique<Node>(*begin)); | |
| insert(++begin, end, *(p.first->second)); | |
| } | |
| } | |
| bool search(string::const_iterator begin, string::const_iterator end, const Node& h) { | |
| if (begin != end) { | |
| auto it = h.childs.find(*begin); | |
| if (it == h.childs.end()) | |
| return false; | |
| else | |
| return search(++begin, end, *(it->second)); | |
| } else { | |
| if (h.childs.find(Node::End) != h.childs.end()) | |
| return true; | |
| else | |
| return false; | |
| } | |
| } | |
| class Trie { | |
| public: | |
| Trie(vector<string>& input) | |
| :head_{' '} | |
| { | |
| for (const auto& e : input) { | |
| ::insert(e.begin(), e.end(), head_); | |
| } | |
| } | |
| void insert(const string& str) { | |
| ::insert(str.begin(), str.end(), head_); | |
| } | |
| bool search(const string& str) const { | |
| return ::search(str.begin(), str.end(), head_); | |
| } | |
| private: | |
| Node head_; | |
| }; | |
| int main() { | |
| vector<string> input {"word1", "hello", "thank you"}; | |
| Trie trie(input); | |
| cout<<trie.search("hello")<<'\n'; | |
| cout<<trie.search("hell")<<'\n'; | |
| assert(trie.search("word11") == false); | |
| assert(trie.search("word") == false); | |
| cout<<trie.search("thank you")<<'\n'; | |
| cout<<trie.search("lamda express")<<'\n'; | |
| trie.insert("lamda express"); | |
| cout<<trie.search("lamda express")<<'\n'; | |
| return 0; | |
| } |
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