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#include <cstdint>
#include <forward_list>
#include <map>
#include <cassert>
#include <iostream>
template <
typename Key
>
class Trie {
public:
typedef std::forward_list<Key> key_list;
Trie():
children_() { }
inline void add(key_list path) {
this->add(path, path.begin());
}
inline void add(
key_list& path,
typename key_list::const_iterator currStep
) {
if ( currStep != path.end() ) {
Trie& trie(
this->children_[*currStep]
);
trie.add(path, ++currStep);
}
}
inline void remove(key_list path) {
this->remove(path, path.begin());
}
inline void remove(
key_list& path,
typename key_list::const_iterator currStep
) {
if ( currStep != path.end() ) {
typename std::map<Key, Trie>::iterator matchingTrie(
this->children_.find(*currStep)
);
if ( matchingTrie != this->children_.end() ) {
typename key_list::const_iterator nextStep(
++currStep
);
if ( (*matchingTrie).second.children_.empty() ||
nextStep == path.end() ) {
this->children_.erase(matchingTrie);
} else {
(*matchingTrie).second.remove(path, nextStep);
}
}
}
}
inline std::pair<bool, const Trie*> resolve(key_list path) const {
return this->resolve(path, path.begin());
}
inline std::pair<bool, const Trie*> resolve(
key_list& path,
typename key_list::const_iterator currStep
) const {
typename std::map<Key, Trie>::const_iterator matchingTrie(
this->children_.find(*currStep)
);
if ( matchingTrie != this->children_.end() ) {
typename key_list::const_iterator nextStep(
++currStep
);
if ( nextStep == path.end() ) {
return std::make_pair(true, &(*matchingTrie).second);
} else {
return (*matchingTrie).second.resolve(path, nextStep);
}
} else {
return std::make_pair(false, nullptr);
}
}
private:
std::map<Key, Trie> children_;
};
int main() {
Trie<uint8_t> test;
test.add({1, 2, 3});
test.add({1, 2, 4});
test.add({2, 1});
test.add({2, 1, 1});
assert(test.resolve({1, 2}).second != nullptr);
assert(test.resolve({1, 2, 3}).second != nullptr);
assert(test.resolve({1, 2, 4}).second != nullptr);
assert(test.resolve({3}).second == nullptr);
test.remove({1, 2});
assert(test.resolve({1, 2, 4}).second == nullptr);
assert(test.resolve({1, 2, 3}).second == nullptr);
assert(test.resolve({1, 2}).second == nullptr);
}
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