Trie data structure on dictionary to find rhyming words

Question

I'm working on my function that would find rhyming words from my dictionary text file that contains 40,000 words. For an example, I enter akes and it gives the words printed would be "rakes sakes takes". So, I know it requires data structure with several variables. Maybe bool would be a better declaration for isWord instead of int? So, the function I'm showing is the modified function because the original function could print only 1 word that rhymes with user's input. So therefore, I would need to build the data structre in Trie version. To be honest, I'm pretty awful with data structure so please bear with me.

struct Node
{
    char c;
    Node* letters[26];
    bool isWord;
};

bool findWords(Node*& pTail, char dictionary[][MaxLength + 1], int numberOfDictionaryWords)
{
    Node* pHead;
    pHead = pTail->letters[26];
    bool found = false;
    int first = 0;
    int last = numberOfDictionaryWords - 1;
    int middle = (first + last) / 2;

    while (first <= last)
    {
        if (strncmp(pHead, dictionary[middle], strlen(pTail)) > 0)
        {
            first = middle + 1;
        }
        else if (strncmp(pHead, dictionary[middle], strlen(pTail)) == 0)
        {
            char theWord[MaxLength + 1];
            memcpy(theWord, dictionary[middle], sizeof(char) * (MaxLength + 1));
            cout << "Words(s) found: " << strReverse(theWord) << endl;
            found = true;
            break;
        }
        else
        {
            last = middle - 1;
        }
        middle = (first + last) / 2;
    }
    return found;
}

int the main():

Node* pTail = NULL;
char dictionary[Rows][MaxLength + 1];
int numberOfWords = 0;
readFile(dictionary, numberOfWords);
sortDictionaryInReverse(dictionary, numberOfWords);
char aWord[MaxLength];
cout << "Enter the suffix to find rhyming words: ";
cin >> aWord;
convertToLowerCase(aWord, strlen(aWord));
strReverse(aWord);

if (findWords(aWord, dictionary, numberOfWords))
{
    cout << "This rhyming word is in the dictionary. \n";
}
else
{
    cout << "This rhyming word is not in the dictionary. \n";
}

The processor usually handles `int` as fast as `bool`. You would only use `bool` for packing, which slows down execution. Have you profiled your code to find out where the bottleneck is? — Thomas Matthews, Nov 26 '14 at 02:01
I suggest you use a different data structure, something more suitable for your purposes. For example, you could have an array of 26 lists or trees, one for each letter. This would reduce your first access to O(1), as you can use the letter to index into the array; no searching involved. — Thomas Matthews, Nov 26 '14 at 02:04

score 0 · Answer 1 · answered Nov 26 '14 at 02:18

I think that a std::multimap would be your best bet.

Your non-words would be the keys and the rhyming words would be the values.

So you could set it up like this:

std::multimap<std::string, std::string> foo;

foo.insert(std::make_pair("akes", "rakes"));
foo.insert(std::make_pair("akes", "sakes"));
foo.insert(std::make_pair("akes", "takes"));

If you wanted to say print out all the rhymes of "akes" you could do:

std::cout << "akes\n\t";
for(auto i = foo.equal_range("akes"); i.first != i.second; ++i.first){
    std::cout << i.first->second << ' ';
}

If you wanted to print out just the first element you could do this:

std::cout << "akes " << foo.find("akes")->second;

Trie data structure on dictionary to find rhyming words

1 Answers1