--- title: LeetCode Diaries #13: One Stack, Zero Jokes | daily.dev description: A casual walkthrough of solving the classic 'Evaluate Reverse Polish Notation' LeetCode problem using a stack-based approach in Python, achieving O(n) time and... canonical: https://daily.dev/posts/leetcode-diaries-13-one-stack-zero-jokes-qy2pvvgox twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: LeetCode Diaries #13: One Stack, Zero Jokes | daily.dev og:description: A casual walkthrough of solving the classic 'Evaluate Reverse Polish Notation' LeetCode problem using a stack-based approach in Python, achieving O(n) time and... og:url: https://daily.dev/posts/leetcode-diaries-13-one-stack-zero-jokes-qy2pvvgox og:image: https://api.daily.dev/og/posts/QY2pVVgOx.png og:image:alt: LeetCode Diaries #13: One Stack, Zero Jokes og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # LeetCode Diaries #13: One Stack, Zero Jokes **[Medium](https://daily.dev/sources/medium_js)** · 4 min read · 0 upvotes · 0 comments ## Summary A casual walkthrough of solving the classic 'Evaluate Reverse Polish Notation' LeetCode problem using a stack-based approach in Python, achieving O(n) time and space complexity. The post explains RPN notation with an example, walks through the parsing logic, and shares the working code, while inviting readers to suggest alternative solutions or puns in the comments. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I evaluate a reverse Polish notation expression using a stack in Python? Parse tokens left to right, pushing operands onto a stack and, on encountering an operator, popping the top two values, applying the operation, and pushing the result back. Convert string tokens to integers before pushing, and for division and subtraction pop the second-popped value first since it appears earlier in the expression. This approach runs in O(n) time and O(n) space, and the final stack value is the answer. _Developers practicing algorithm interview problems can browse similar stack-based solutions on daily.dev._ ## Similar posts on daily.dev - [The Code Started Writing Itself After Thinking Like a Program Instead of a Human](https://daily.dev/posts/the-code-started-writing-itself-after-thinking-like-a-program-instead-of-a-human-5vxqsapej) · Medium · 0 upvotes · 0 comments - [Indexed Reverse Polish Notation, an Alternative to AST](https://daily.dev/posts/indexed-reverse-polish-notation-an-alternative-to-ast-9hndkk9lz) · Lobsters · 1 upvotes · 0 comments - [Python Stacks, Queues, and Priority Queues in Practice Quiz – Real Python](https://daily.dev/posts/python-stacks-queues-and-priority-queues-in-practice-quiz-real-python-ymniqiwip) · Real Python · 0 upvotes · 0 comments - [Coderbyte \#2: Bracket Combinations Challenge in Python](https://daily.dev/posts/coderbyte-2-bracket-combinations-challenge-in-python-i9obh3yg9) · Medium · 1 upvotes · 0 comments --- Tags: [#python](https://daily.dev/tags/python) [View this post on daily.dev](https://daily.dev/posts/leetcode-diaries-13-one-stack-zero-jokes-qy2pvvgox) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"LeetCode Diaries #13: One Stack, Zero Jokes","url":"https://daily.dev/posts/leetcode-diaries-13-one-stack-zero-jokes-qy2pvvgox","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/leetcode-diaries-13-one-stack-zero-jokes-qy2pvvgox"},"datePublished":"2026-08-21T16:10:12.329Z","dateModified":"2026-08-21T16:36:18.786Z","description":"A casual walkthrough of solving the classic 'Evaluate Reverse Polish Notation' LeetCode problem using a stack-based approach in Python, achieving O(n) time and...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/50e235215ecef5b7caa8c933595fa6fd?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/50e235215ecef5b7caa8c933595fa6fd?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Medium","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Medium","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/medium","url":"https://daily.dev/sources/medium_js"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/leetcode-diaries-13-one-stack-zero-jokes-qy2pvvgox","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"python","timeRequired":"PT4M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Medium","item":"https://daily.dev/sources/medium_js"},{"@type":"ListItem","position":3,"name":"LeetCode Diaries #13: One Stack, Zero Jokes"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/leetcode-diaries-13-one-stack-zero-jokes-qy2pvvgox#faq","mainEntity":[{"@type":"Question","name":"How do I evaluate a reverse Polish notation expression using a stack in Python?","acceptedAnswer":{"@type":"Answer","text":"Parse tokens left to right, pushing operands onto a stack and, on encountering an operator, popping the top two values, applying the operation, and pushing the result back. 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