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-rw-r--r--trie.cc76
1 files changed, 76 insertions, 0 deletions
diff --git a/trie.cc b/trie.cc
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+#include <cstdint>
+#include <forward_list>
+#include <map>
+#include <memory>
+
+#include <cassert>
+#include <iostream>
+
+template <
+ typename Key
+>
+class Trie {
+ public:
+ typedef std::unique_ptr<Trie> ptr;
+
+ Trie():
+ children_() { }
+
+ inline void add(std::forward_list<Key> path) {
+ this->add(path, path.begin());
+ }
+
+ inline void add(std::forward_list<Key>& path,
+ typename std::forward_list<Key>::const_iterator curr) {
+ if ( curr != path.end() ) {
+ Trie::ptr& trie = this->children_[*curr];
+
+ if ( trie ) {
+ trie->add(path, ++curr);
+ } else {
+ trie.reset(new Trie<Key>());
+ trie->add(path, ++curr);
+ }
+ }
+ }
+
+ inline Trie* resolve(std::forward_list<Key> path) const {
+ return this->resolve(path, path.begin());
+ }
+
+ inline Trie* resolve(
+ std::forward_list<Key>& path,
+ typename std::forward_list<Key>::const_iterator curr
+ ) const {
+ auto trie = this->children_.find(*curr);
+
+ if ( trie != this->children_.end() ) {
+ auto next = ++curr;
+
+ if ( next == path.end() ) {
+ return (*trie).second.get();
+ } else {
+ return (*trie).second->resolve(path, next);
+ }
+ } else {
+ return nullptr;
+ }
+ }
+
+ protected:
+ std::map<Key, Trie::ptr> children_;
+
+};
+
+int main() {
+ Trie<uint8_t> test;
+
+ test.add(std::forward_list<uint8_t>{1, 2, 3});
+ test.add(std::forward_list<uint8_t>{1, 2, 4});
+ test.add(std::forward_list<uint8_t>{2, 1});
+ test.add(std::forward_list<uint8_t>{2, 1, 1});
+
+ assert(test.resolve(std::forward_list<uint8_t>{1, 2}) != nullptr);
+ assert(test.resolve(std::forward_list<uint8_t>{1, 2, 4}) != nullptr);
+ assert(test.resolve(std::forward_list<uint8_t>{3}) == nullptr);
+}