使用Trie实施字典

使用Trie实现字典，以便如果输入是代表单词的字符串，则程序将从预建的字典中打印其含义。

例子：

Input: str = “map”
Output: a diagrammatic representation of an area

Input: str = “language”
Output: the method of human communication

方法：我们可以使用Trie有效地存储和搜索字符串。在此，讨论了使用Trie的字典的实现(使用哈希图的内存优化)。我们添加一个字段到字典树节点，一个字符串，将举行一个词的含义。在搜索所需单词的含义时，我们在Trie中搜索单词，如果该单词存在(即isEndOfWord = true)，则返回其含义，否则返回空字符串。

下面是上述方法的实现：

// C++ implementation of the approach
#include 
using namespace std;
  
// Structure for Trie
struct Trie {
    bool isEndOfWord;
    unordered_map map;
    string meaning;
};
  
// Function to create a new Trie node
Trie* getNewTrieNode()
{
    Trie* node = new Trie;
    node->isEndOfWord = false;
    return node;
}
  
// Function to insert a word with its meaning
// in the dictionary built using a Trie
void insert(Trie*& root, const string& str,
            const string& meaning)
{
  
    // If root is null
    if (root == NULL)
        root = getNewTrieNode();
  
    Trie* temp = root;
    for (int i = 0; i < str.length(); i++) {
        char x = str[i];
  
        // Make a new node if there is no path
        if (temp->map.find(x) == temp->map.end())
            temp->map[x] = getNewTrieNode();
  
        temp = temp->map[x];
    }
  
    // Mark end of word and store the meaning
    temp->isEndOfWord = true;
    temp->meaning = meaning;
}
  
// Function to search a word in the Trie
// and return its meaning if the word exists
string getMeaning(Trie* root, const string& word)
{
  
    // If root is null i.e. the dictionary is empty
    if (root == NULL)
        return "";
  
    Trie* temp = root;
  
    // Search a word in the Trie
    for (int i = 0; i < word.length(); i++) {
        temp = temp->map[word[i]];
        if (temp == NULL)
            return "";
    }
  
    // If it is the end of a valid word stored
    // before then return its meaning
    if (temp->isEndOfWord)
        return temp->meaning;
    return "";
}
  
// Driver code
int main()
{
    Trie* root = NULL;
  
    // Build the dictionary
    insert(root, "language", "the method of human communication");
    insert(root, "computer", "A computer is a machine that can be \
    instructed to carry out sequences of arithmetic or \
logical operations automatically via computer programming");
    insert(root, "map", "a diagrammatic representation \
of an area");
    insert(root, "book", "a written or printed work \
consisting of pages glued or sewn together along one \
side and bound in covers.");
    insert(root, "science", "the intellectual and \
practical activity encompassing the systematic study \
of the structure and behaviour of the physical and \
natural world through observation and experiment.");
  
    string str = "map";
    cout << getMeaning(root, str);
  
    return 0;
}

输出：

a diagrammatic representation of an area