고성능 데이터베이스 검색 알고리즘을 위한 Java 구현 기술 분석 및 공유

public class BinarySearch {
    public static int binarySearch(int[] arr, int target) {
        int left = 0;
        int right = arr.length - 1;

        while (left <= right) {
            int mid = left + (right - left) / 2;

            if (arr[mid] == target) {
                return mid;
            } else if (arr[mid] < target) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }

        return -1;
    }

    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
        int target = 5;

        int index = binarySearch(arr, target);
        if (index != -1) {
            System.out.println("找到目标元素，索引为：" + index);
        } else {
            System.out.println("未找到目标元素");
        }
    }
}

public class BlockSearch {
    public static int blockSearch(int[] arr, int[] blocks, int target) {
        int blockIndex = binarySearch(blocks, target);

        if (blockIndex == -1) {
            return -1;
        }

        int startIndex = blockIndex > 0 ? blocks[blockIndex - 1] : 0;
        int endIndex = blocks[blockIndex];

        for (int i = startIndex; i < endIndex; i++) {
            if (arr[i] == target) {
                return i;
            }
        }

        return -1;
    }

    public static int binarySearch(int[] arr, int target) {
        int left = 0;
        int right = arr.length - 1;

        while (left <= right) {
            int mid = left + (right - left) / 2;

            if (arr[mid] == target) {
                return mid;
            } else if (arr[mid] < target) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }

        return -1;
    }

    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
        int[] blocks = {5, 10};
        int target = 5;

        int index = blockSearch(arr, blocks, target);
        if (index != -1) {
            System.out.println("找到目标元素，索引为：" + index);
        } else {
            System.out.println("未找到目标元素");
        }
    }
}

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class InvertedIndex {
    public static Map<String, List<Integer>> buildInvertedIndex(List<String> documents) {
        Map<String, List<Integer>> invertedIndex = new HashMap<>();

        for (int i = 0; i < documents.size(); i++) {
            String[] words = documents.get(i).split(" ");

            for (String word : words) {
                if (!invertedIndex.containsKey(word)) {
                    invertedIndex.put(word, new ArrayList<>());
                }
                List<Integer> docList = invertedIndex.get(word);
                docList.add(i);
            }
        }

        return invertedIndex;
    }

    public static List<Integer> searchInvertedIndex(Map<String, List<Integer>> invertedIndex, String keyword) {
        if (!invertedIndex.containsKey(keyword)) {
            return new ArrayList<>();
        }

        return invertedIndex.get(keyword);
    }

    public static void main(String[] args) {
        List<String> documents = new ArrayList<>();
        documents.add("Java is a programming language.");
        documents.add("Python is a popular language for machine learning.");
        documents.add("Java and Python are both widely used languages.");

        Map<String, List<Integer>> invertedIndex = buildInvertedIndex(documents);

        List<Integer> result = searchInvertedIndex(invertedIndex, "Java");
        if (!result.isEmpty()) {
            System.out.println("搜索到目标关键词，所在文档索引为：" + result);
        } else {
            System.out.println("未搜索到目标关键词");
        }
    }
}