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| class Trie {
private:
struct TrieNode {
TrieNode(): is_word(false), children(26, nullptr) {}
~TrieNode() {
for (TrieNode* child : children)
if (child) delete child;
}
bool is_word;
vector<TrieNode*> children;
};
const TrieNode* find(const string& prefix) const {
const TrieNode* p = root_.get();
for (const char c : prefix) {
p = p->children[c - 'a'];
if (p == nullptr) break;
}
return p;
}
public:
std::unique_ptr<TrieNode> root_;
Trie():root_(new TrieNode()) {}
void insert(string word) {
TrieNode* p = root_.get();
for (const char c : word) {
if (!p->children[c - 'a'])
p->children[c - 'a'] = new TrieNode();
p = p->children[c - 'a'];
}
p->is_word = true;
}
bool search(string word) {
const TrieNode* p = find(word);
return p && p->is_word;
}
bool startsWith(string prefix) {
return find(prefix) != nullptr;
}
};
|