https://leetcode.com/problems/implement-trie-prefix-tree/#/description
实现前缀树。
class TrieNode {
public:
bool is_word;
TrieNode* next[26];
TrieNode() : is_word{false} {
for (int i = 0; i < 26; ++i) {
next[i] = NULL;
}
}
};
class Trie {
public:
/** Initialize your data structure here. */
Trie() {
root = new TrieNode();
}
/** Inserts a word into the trie. */
void insert(string word) {
if (word.empty()) return;
TrieNode* p = root;
for (char c : word) {
if (!p->next[c-'a']) {
p->next[c-'a'] = new TrieNode();
}
p = p->next[c-'a'];
}
p->is_word = true;
}
/** Returns if the word is in the trie. */
bool search(string word) {
if (word.empty()) return false;
TrieNode* p = root;
for (char c : word) {
p = p->next[c-'a'];
if (!p) return false;
}
if (!p->is_word) return false;
return true;
}
/** Returns if there is any word in the trie that starts with the given prefix. */
bool startsWith(string prefix) {
if (prefix.empty()) return true;
TrieNode* p = root;
for (char c : prefix) {
p = p->next[c-'a'];
if (!p) return false;
}
return true;
}
private:
TrieNode* root;
};