> For the complete documentation index, see [llms.txt](https://liuzhenglaichn.gitbook.io/algorithm/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://liuzhenglaichn.gitbook.io/algorithm/offline-query.md). # Offline Query A common trick for solving problems related to a series of queries. When we know all the queries upfront, we can sort the query and the original data in some order so that we can scan the query and the original data simultaneously (which takes `O(N + Q)` time), instead of scanning all original data for each query (which takes `O(N * Q)` time). The name "offline" signifies the fact that we know all the queries upfront/offline. If the queries keep streaming in (i.e. online), we can't reorder the queries to get a better time complexity. ## Problems * [1707. Maximum XOR With an Element From Array (Hard)](https://leetcode.com/problems/maximum-xor-with-an-element-from-array/) * [1847. Closest Room (Hard)](https://leetcode.com/problems/closest-room/) * [2070. Most Beautiful Item for Each Query (Medium)](https://leetcode.com/problems/most-beautiful-item-for-each-query/) ## Discuss --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://liuzhenglaichn.gitbook.io/algorithm/offline-query.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.