Mar 13 · 14 min read · TLDR: Search autocomplete must respond in sub-10ms to feel "instant." The core trade-off is Latency vs. Data Freshness: we use an offline pipeline (Spark) to pre-calculate prefix-to-suggestion mappings and store them in Redis Sorted Sets (or a specia...
Join discussionJan 17 · 3 min read · Problem You are given an array nums consisting of non-negative integers. You are also given a queries array, where queries[i] = [x<sub>i</sub>, m<sub>i</sub>]. (link) The answer to the i<sup>th</sup> query is the maximum bitwise XOR value of x<sub>i<...
Join discussionJan 15 · 2 min read · Problem Given an integer array nums, return the maximum result of nums[i] XOR nums[j], where 0 <= i <= j < n. (link) Example 1: Input: nums = [3,10,5,25,2,8] Output: 28 Explanation: The maximum result is 5 XOR 25 = 28. Example 2: Input: nums = [14,7...
Join discussionJan 15 · 2 min read · Problem Given a string s consisting of lowercase English characters, determine the total number of distinct non-empty substrings present in the string. A substring is defined as a contiguous block of characters within the string. Two substrings are c...
Join discussionJan 15 · 2 min read · Problem Given an array of strings words[], find the longest string such that every prefix of it is also present in words[]. If multiple strings have the same maximum length, return the lexicographically smallest one. (link) If no such string is found...
Join discussionJan 11 · 3 min read · Problem Ninja has to implement a data structure ”TRIE” from scratch. Ninja has to complete some functions. 1) Trie(): Ninja has to initialize the object of this “TRIE” data structure. 2) insert(“WORD”): Ninja has to insert the string “WORD” into th...
Join discussionJan 4 · 3 min read · Problem A trie (pronounced as "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker. (link) Imp...
Join discussionOct 3, 2025 · 3 min read · 一提到字符串相关的问题，尤其是涉及前缀匹配的，很多人的第一反应可能是哈希表，或者直接用字符串的 startsWith 方法循环遍历。这些方法当然可以，但一旦数据量上来，或者查询变得频繁，性能问题就暴露无遗了。今天，我们就从这个痛点出发，一步步揭开字典树的神秘面纱，看看它是如何优雅地解决这类问题的。 故事的开始：一个简单的需求 我们先来看一个具体的需求。假设我们正在开发一个搜索框的输入提示功能。我们需要实现这么几个 API： insert(String word): 添加一个新的词到我们的词库里...
Join discussionSep 7, 2025 · 10 min read · A search engine, as the name suggests, is a tool that helps you search through your content. It efficiently retrieves relevant information from a vast pool of data, allowing users to find specific documents, web pages, or files quickly. By indexing c...
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