Implement a trie with insert, search, and startsWith methods.
Note:
You may assume that all inputs are consist of lowercase letters a-z.
Hide Tags Data Structure Trie
实现一棵Trie树以及实现查询的功能,根据上一篇文章中的分析和伪代码可以很迅速地实现:
runtime:68ms
class TrieNode {
public:
// Initialize your data structure here.
TrieNode() {
words=0;
prefixs=0;
for(int i=0;i<26;i++)
edges[i]=NULL;
}
int words;
int prefixs;
TrieNode* edges[26];
};
class Trie {
public:
Trie() {
root = new TrieNode();
}
// Inserts a word into the trie.
void insert(string word) {
insertHelper(root,word,0);
}
// Returns if the word is in the trie.
bool search(string word) {
return searchHelper(root,word,0)!=0;
}
// Returns if there is any word in the trie
// that starts with the given prefix.
bool startsWith(string prefix) {
return startsWithHelper(root,prefix,0)!=0;
}
void insertHelper(TrieNode * node,string &word,int pos) {
if(pos==word.size())
{
node->words++;
node->prefixs++;
}
else
{
node->prefixs++;
int char_code=word[pos]-‘a‘;
if(node->edges[char_code]==NULL)
node->edges[char_code]=new TrieNode();
insertHelper(node->edges[char_code],word,pos+1);
}
}
int searchHelper(TrieNode * node,string &word,int pos)
{
int char_code=word[pos]-‘a‘;
if(pos==word.size())
return node->words;
else if(node->edges[char_code]==NULL)
return 0;
else
return searchHelper(node->edges[char_code],word,pos+1);
}
int startsWithHelper(TrieNode * node,string &word,int pos)
{
int char_code=word[pos]-‘a‘;
if(pos==word.size())
return node->prefixs;
else if(node->edges[char_code]==NULL)
return 0;
else
return startsWithHelper(node->edges[char_code],word,pos+1);
}
private:
TrieNode* root;
};
// Your Trie object will be instantiated and called as such:
// Trie trie;
// trie.insert("somestring");
// trie.search("key");
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时间: 2024-11-03 05:40:59