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trie.cpp
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trie.cpp
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#include <unordered_map>
#include <iostream>
#include <memory>
#include <array>
using namespace std;
class trie
{
private:
struct node
{
node() : words(0), prefixes(0)
{ }
int words;
int prefixes;
std::unordered_map<char, std::unique_ptr<node>> edges;
};
void addWord(node &e, const std::string &s, int i)
{
if(i == (int)s.size())
{
e.words++;
return;
}
e.prefixes++;
if(e.edges[s[i]] == nullptr)
e.edges[s[i]] = std::unique_ptr<node>(new node());
addWord(*e.edges[s[i]], s, i+1);
}
int countWords(node &e, const std::string &s, int i)
{
if(i == (int)s.size())
return e.words;
if(e.edges[s[i]] == nullptr)
return 0;
return countWords(*e.edges[s[i]], s, i+1);
}
int countPrefixes(node &e, const std::string &s, int i)
{
if(i == (int)s.size())
return e.prefixes;
if(e.edges[s[i]] == nullptr)
return 0;
return countPrefixes(*e.edges[s[i]], s, i+1);
}
node root;
public:
trie(){ };
void addWord(const std::string &s)
{
addWord(root, s, 0);
}
int countWords(const std::string &s)
{
return countWords(root, s, 0);
}
int countPrefixes(const std::string &s)
{
return countPrefixes(root, s, 0);
}
};
int main()
{
trie t;
t.addWord("");
t.addWord("abc");
t.addWord("abcd");
t.addWord("cat");
t.addWord("dog");
t.addWord("doggy");
t.addWord("dog");
t.addWord("doggies");
t.addWord("przemyslawisawesome");
cout << t.countWords("dog") << endl;
cout << t.countPrefixes("do") << endl;
}