--- title: Optimal File Merge Using Min Heap in Java | daily.dev description: Merging multiple files into one at minimum total cost requires always combining the two smallest files first. This greedy strategy keeps intermediate file... canonical: https://daily.dev/posts/optimal-file-merge-using-min-heap-in-java-fu1dpu1u5 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Optimal File Merge Using Min Heap in Java | daily.dev og:description: Merging multiple files into one at minimum total cost requires always combining the two smallest files first. This greedy strategy keeps intermediate file... og:url: https://daily.dev/posts/optimal-file-merge-using-min-heap-in-java-fu1dpu1u5 og:image: https://api.daily.dev/og/posts/Fu1dpu1u5.png og:image:alt: Optimal File Merge Using Min Heap in Java 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. # Optimal File Merge Using Min Heap in Java **[C\# Corner](https://daily.dev/sources/csharpcorner)** · 3 min read · 0 upvotes · 0 comments ## Summary Merging multiple files into one at minimum total cost requires always combining the two smallest files first. This greedy strategy keeps intermediate file sizes small, since a large merged file otherwise contributes to the cost repeatedly. For files [3, 2, 4], merging 2+3=5 then 5+4=9 gives a total cost of 14, cheaper than merging 3+4=7 then 7+2=9 for 16. Java's PriorityQueue acts as a min heap by default, so pq.poll() always returns the smallest element, letting you repeatedly pull and merge the two smallest sizes until one file remains. ## 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 use a min heap to solve the optimal file merge problem in Java? Use Java's PriorityQueue, which is a min heap by default, to always merge the two smallest files first. Insert all file sizes into the queue, then while more than one element remains, poll the two smallest values, add them together, accumulate that sum into a total cost, and insert the merged value back into the queue until one remains. _Developers implementing merge-cost algorithms can find worked Java examples like this on daily.dev._ ### Why does merging the two smallest files first minimize total file merge cost? Merging the two smallest files first keeps intermediate file sizes as small as possible, since any merged file becomes part of future merges and its size contributes to the total cost multiple times. For files sized 3, 2, and 4, merging 2+3=5 then 5+4=9 gives a total cost of 14, compared to 16 if 3 and 4 are merged first. _Anyone comparing greedy algorithm strategies can weigh trade-offs like this one on daily.dev._ ### Does Java's PriorityQueue return the smallest or largest element by default? Java's PriorityQueue returns the smallest element by default, functioning as a min heap. Calling pq.poll() on a queue built from PriorityQueue pq = new PriorityQueue<>() always returns the current smallest value in the queue, which is why it suits algorithms like optimal file merge that repeatedly need the smallest elements. _Java developers double-checking PriorityQueue behavior can revisit concrete explanations like this on daily.dev._ ## Similar posts on daily.dev - [Generational Priority Queues](https://daily.dev/posts/generational-priority-queues-cfetbb4hc) · Awesome Java Newsletter · 2 upvotes · 0 comments - [Algorithms in Java Series](https://daily.dev/posts/algorithms-in-java-series-4c0hui0mq) · Baeldung · 24 upvotes · 1 comments - [PivCo-Huffman “merge” operations](https://daily.dev/posts/pivco-huffman-merge-operations-ypm0kxiih) · Ryg blog · 0 upvotes · 0 comments - [Parallelizing ClickHouse aggregation merge for fixed hash map](https://daily.dev/posts/parallelizing-clickhouse-aggregation-merge-for-fixed-hash-map-lafktzvpq) · ClickHouse · 2 upvotes · 0 comments --- Tags: [#java](https://daily.dev/tags/java) [View this post on daily.dev](https://daily.dev/posts/optimal-file-merge-using-min-heap-in-java-fu1dpu1u5) ```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":"Optimal File Merge Using Min Heap in Java","url":"https://daily.dev/posts/optimal-file-merge-using-min-heap-in-java-fu1dpu1u5","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/optimal-file-merge-using-min-heap-in-java-fu1dpu1u5"},"datePublished":"2026-10-29T05:22:44.901Z","dateModified":"2026-10-29T05:23:09.718Z","description":"Merging multiple files into one at minimum total cost requires always combining the two smallest files first. 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