C++ 语言搜索引擎核心算法示例解析
随着互联网的快速发展，搜索引擎已经成为人们获取信息的重要工具。C++ 作为一种高性能的编程语言，在搜索引擎的核心算法实现中扮演着重要角色。本文将围绕 C++ 语言，探讨搜索引擎核心算法的示例实现，包括关键词提取、倒排索引构建、搜索算法等。
关键词提取
关键词提取是搜索引擎的第一步，它能够帮助我们快速定位到用户感兴趣的内容。以下是一个简单的关键词提取算法示例：
cpp
include
include
include
include
include
std::vector extractKeywords(const std::string& text) {
std::vector keywords;
std::unordered_map wordCount;
std::istringstream iss(text);
std::string word;
while (iss >> word) {
// 去除标点符号
word.erase(std::remove_if(word.begin(), word.end(), ::ispunct), word.end());
// 转换为小写
std::transform(word.begin(), word.end(), word.begin(), ::tolower);
// 统计词频
++wordCount[word];
}
// 提取高频关键词
for (const auto& pair : wordCount) {
if (pair.second > 1) {
keywords.push_back(pair.first);
}
}
return keywords;
}
int main() {
std::string text = "C++ is a powerful programming language used in many applications, including search engines.";
std::vector keywords = extractKeywords(text);
for (const auto& keyword : keywords) {
std::cout << keyword << std::endl;
}
return 0;
}
倒排索引构建
倒排索引是搜索引擎的核心数据结构，它将文档中的词语映射到包含这些词语的文档列表。以下是一个简单的倒排索引构建算法示例：
cpp
include
include
include
include
class InvertedIndex {
private:
std::unordered_map<#std::string, std::vector> index;
public:
void addDocument(int docId, const std::string& text) {
std::istringstream iss(text);
std::string word;
while (iss >> word) {
// 去除标点符号
word.erase(std::remove_if(word.begin(), word.end(), ::ispunct), word.end());
// 转换为小写
std::transform(word.begin(), word.end(), word.begin(), ::tolower);
index[word].push_back(docId);
}
}
const std::vector& getDocumentsForWord(const std::string& word) const {
return index.at(word);
}
};
int main() {
InvertedIndex index;
index.addDocument(1, "C++ is a powerful programming language.");
index.addDocument(2, "C++ is used in many applications.");
index.addDocument(3, "Search engines are built with C++.");
std::string query = "C++";
std::vector documents = index.getDocumentsForWord(query);
for (int docId : documents) {
std::cout << "Document " << docId << " contains the word '" << query << "'." << std::endl;
}
return 0;
}
搜索算法
搜索算法是搜索引擎的核心功能，它根据用户的查询返回最相关的文档列表。以下是一个简单的搜索算法示例：
cpp
include
include
include
include
include
std::vector search(const InvertedIndex& index, const std::string& query) {
std::unordered_map score;
std::istringstream iss(query);
std::string word;
while (iss >> word) {
// 去除标点符号
word.erase(std::remove_if(word.begin(), word.end(), ::ispunct), word.end());
// 转换为小写
std::transform(word.begin(), word.end(), word.begin(), ::tolower);
const auto& documents = index.getDocumentsForWord(word);
for (int docId : documents) {
++score[docId];
}
}
std::vector sortedScores(score.begin(), score.end());
std::sort(sortedScores.begin(), sortedScores.end(), [](const std::pair& a, const std::pair& b) {
return a.second > b.second;
});
std::vector results;
for (const auto& pair : sortedScores) {
results.push_back(pair.first);
}
return results;
}
int main() {
InvertedIndex index;
index.addDocument(1, "C++ is a powerful programming language.");
index.addDocument(2, "C++ is used in many applications.");
index.addDocument(3, "Search engines are built with C++.");
std::string query = "C++";
std::vector results = search(index, query);
for (int docId : results) {
std::cout << "Document " << docId << " is relevant to the query." << std::endl;
}
return 0;
}
总结
本文通过 C++ 语言，展示了搜索引擎核心算法的示例实现，包括关键词提取、倒排索引构建和搜索算法。这些示例虽然简单，但它们为理解搜索引擎的工作原理提供了基础。在实际应用中，搜索引擎的算法会更加复杂，涉及更多高级技术和优化策略。
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