Every TrieNode stores one letter, there are alph_size of children in each layer. Root doesn't store any letter, the last leaf stores isEndOfWord other than letter.
class TrieNode {
public:
TrieNode *child[26];
bool isWord;
};
class TrieNode {
public:
TrieNode *child[26];
bool isWord;
TrieNode(): isWord(false) {
for(auto &a : child) a = nullptr;
}
};
class Trie {
public:
/** Initialize your data structure here. */
Trie() {
root = new TrieNode();
}
/** Inserts a word into the trie. */
void insert(string word) {
TrieNode *p = root;
for(auto &a : word) {
int i = a - 'a';
if(!p->child[i]) p->child[i] = new TrieNode();
p = p->child[i];
}
p->isWord = true;
}
/** Returns if the word is in the trie. */
bool search(string word) {
TrieNode *p = root;
for(auto &a : word) {
int i = a - 'a';
if(!p->child[i]) return false; // if the child is ended
p = p->child[i];
}
return p->isWord;
}
/** Returns if there is any word in the trie that starts with the given prefix. */
bool startsWith(string prefix) {
TrieNode *p = root;
for(auto &a : prefix) {
int i = a - 'a';
if(!p->child[i]) return false;
p = p->child[i];
}
return true;
}
private:
TrieNode *root;
};
/**
* Your Trie object will be instantiated and called as such:
* Trie* obj = new Trie();
* obj->insert(word);
* bool param_2 = obj->search(word);
* bool param_3 = obj->startsWith(prefix);
*/
for(auto &a : s) 的用法注意了，是只能用指针么？
"T" means isEndOfWord = True. Refer to https://www.geeksforgeeks.org/trie-insert-and-search/
