Inverted Index

Create an inverted index with given documents.

这是一道字符串相关的题目，实际上并不难，其中的一个主要的问题是正则表达式的使用，对于java来说可以直接使用string中的方法split（“\\s+”）作为切分方式，在python需要导入re模块

java

/** * Definition of Document: * class Document { *     public int id; *     public String content; * } */public class Solution {    /**     * @param docs a list of documents     * @return an inverted index     */    public Map<String, List<Integer>> invertedIndex(List<Document> docs) {        // Write your code here        Map<String, List<Integer>> map = new HashMap<>();        int id;        String str;        String[] arr;        for (int i = 0; i < docs.size(); i++) {            id = docs.get(i).id;            str = docs.get(i).content;            arr = str.trim().split("\\s+");            for (int j = 0; j < arr.length; j++) {                util(map, arr[j], id);            }        }        return map;    }        private void util(Map<String, List<Integer>> map,                       String str,                       int id) {        if (!map.containsKey(str)) {            List<Integer> list = new ArrayList<>();            list.add(id);            map.put(str, list);        } else {            List<Integer> list = map.get(str);            if (list.get(list.size() - 1) == id) {                return;            } else {                list.add(id);                map.put(str, list);            }        }    }}

python

'''Definition of Documentclass Document:    def __init__(self, id, cotent):        self.id = id        self.content = content'''import reclass Solution:    # @param {Document[]} docs a list of documents    # @return {dict(string, int[])} an inverted index    def invertedIndex(self, docs):        # Write your code here        mapping = {}        for i in range(len(docs)):            idd = docs[i].id            content = docs[i].content.strip()            arr = re.split('\\s+', content)            for ele in arr:                self.util(mapping, ele, idd)        return mapping            def util(self, mapping, string, idd):        if string not in mapping:            mapping[string] = [idd]        else:            path = mapping[string]            if path[-1] == idd:                return             else:                path.append(idd)                mapping[string] = path