{"id":17414,"date":"2022-10-24T14:21:01","date_gmt":"2022-10-24T08:51:01","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/"},"modified":"2022-10-24T14:21:01","modified_gmt":"2022-10-24T08:51:01","slug":"solved-high-performance-merging-of-ordered-sets","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/","title":{"rendered":"[Solved] High-performance merging of ordered sets"},"content":{"rendered":"

[ad_1]
\n<\/p>\n

\n
\n
<\/div>\n
\n
\n

This is not going to be the fastest data structure & algorithm for your particular purpose I guess, but it may be fast enough. Test it yourself.<\/p>\n

Note that a std::forward_list<\/code> or even a std::vector<\/code> might be faster depending on the actual scenario (-> constant factors in big-O-notation).<\/p>\n

tmyklebu mentioned another approach in the comments: depending on the scenario, it might be faster to merge on-demand, e.g. storing all data sets individually and merging them into a vector<\/code> to pass to the event handler, or even using a “merging” iterator (whose increment gets the next element of the individual data sets).<\/p>\n

Further performance improvements may be achieved by using a custom memory pool -> custom allocator.<\/p>\n

#include <set>\n#include <iostream>\n#include <iterator>\n#include <algorithm>\n\n\/\/ inserts a sorted range into the `to` container\ntemplate < typename To, typename InputIt >\nvoid insert_new_sorted(To& to,\n                       InputIt beg_old, InputIt end_old,\n                       InputIt beg_new, InputIt end_new)\n{\n    auto const& comp = to.value_comp();\n    typename To::iterator i = to.begin();\n\n    \/\/ might improve performance: don't remove elements which are in both\n    \/\/ ranges (old and new)\n    while(beg_old != end_old && beg_new != end_new)\n    {\n        if(comp(*beg_old, *beg_new))\n        {\n            \/\/ remove old element\n            i = to.find(*beg_old);  \/\/ \"slow\", no hint :(\n            i = to.erase(i);\n            ++beg_old;\n        }else if(comp(*beg_new, *beg_old))\n        {\n            \/\/ insert new element\n            \/\/ using the hint to achieve better performance\n            i = to.insert(i, *beg_new);\n            ++beg_new;\n        }else\n        {\n            \/\/ both equal, do nothing\n            ++beg_new;\n            ++beg_old;\n        }\n    }\n\n    \/\/ remove remaining old elements\n    for(; beg_old != end_old; ++beg_old)\n    {\n        to.erase(to.find(*beg_old));  \/\/ \"slow\", no hint :(\n    }\n\n    \/\/ insert remaining new elements\n    for(; beg_new != end_new; ++beg_new)\n    {\n        i = to.insert(i, *beg_new);\n    }\n\n    std::copy(to.begin(), to.end(),\n        std::ostream_iterator<typename To::value_type>(std::cout, \", \"));\n    std::cout << std::endl;\n}\n\nint main()\n{\n    using set_t = std::multiset<double>;\n\n    set_t const A = {1, 3, 4, 6};\n    set_t const B = {1, 2, 3};\n    set_t const C = {2, 3, 5};\n    set_t const A2 = {2, 4, 7, 8};\n\n    set_t result;\n    insert_new_sorted(result, A.end(), A.end(), A.begin(), A.end());\n    insert_new_sorted(result, B.end(), B.end(), B.begin(), B.end());\n    insert_new_sorted(result, C.end(), C.end(), C.begin(), C.end());\n    insert_new_sorted(result, A.begin(), A.end(), A2.begin(), A2.end());\n}\n<\/code><\/pre>\n
Output:<\/p>\n
\n
1, 3, 4, 6, 
\n  1, 1, 2, 3, 3, 4, 6, 
\n  1, 1, 2, 2, 3, 3, 3, 4, 5, 6, 
\n  1, 2, 2, 2, 3, 3, 4, 5, 7, 8, <\/p>\n<\/blockquote>\n
\n
A different approach: store the iterators of the inserted elements, to speed up erasing.<\/p>\n<\/p><\/div>\n
<\/div>\n<\/div>\n
            6<\/span> <\/p><\/div>\n<\/div>\n
[ad_2]<\/p>\n
solved High-performance merging of ordered sets <\/p>\n","protected":false},"excerpt":{"rendered":"
[ad_1] This is not going to be the fastest data structure & algorithm for your particular purpose I guess, but it may be fast enough. Test it yourself. Note that a std::forward_list or even a std::vector might be faster depending on the actual scenario (-> constant factors in big-O-notation). tmyklebu mentioned another approach in the … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[457,513,325,4323,561],"class_list":["post-17414","post","type-post","status-publish","format-standard","hentry","category-solved","tag-algorithm","tag-c11","tag-performance","tag-real-time-updates","tag-sorting"],"yoast_head":"\n[Solved] High-performance merging of ordered sets - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] High-performance merging of ordered sets - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] This is not going to be the fastest data structure & algorithm for your particular purpose I guess, but it may be fast enough. Test it yourself. Note that a std::forward_list or even a std::vector might be faster depending on the actual scenario (-> constant factors in big-O-notation). tmyklebu mentioned another approach in the ... Read more\" \/>\n<meta property=\"og:url\" content=\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/\" \/>\n<meta property=\"og:site_name\" content=\"JassWeb\" \/>\n<meta property=\"article:published_time\" content=\"2022-10-24T08:51:01+00:00\" \/>\n<meta name=\"author\" content=\"Kirat\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Kirat\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/\"},\"author\":{\"name\":\"Kirat\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31\"},\"headline\":\"[Solved] High-performance merging of ordered sets\",\"datePublished\":\"2022-10-24T08:51:01+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/\"},\"wordCount\":145,\"publisher\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\"},\"keywords\":[\"algorithm\",\"c++11\",\"performance\",\"real-time-updates\",\"sorting\"],\"articleSection\":[\"Solved\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/\",\"url\":\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/\",\"name\":\"[Solved] High-performance merging of ordered sets - JassWeb\",\"isPartOf\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#website\"},\"datePublished\":\"2022-10-24T08:51:01+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/jassweb.com\/solved\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"[Solved] High-performance merging of ordered sets\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/jassweb.com\/solved\/#website\",\"url\":\"https:\/\/jassweb.com\/solved\/\",\"name\":\"JassWeb\",\"description\":\"Build High-quality Websites\",\"publisher\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/jassweb.com\/solved\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\",\"name\":\"Jass Web\",\"url\":\"https:\/\/jassweb.com\/solved\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png\",\"contentUrl\":\"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png\",\"width\":693,\"height\":132,\"caption\":\"Jass Web\"},\"image\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31\",\"name\":\"Kirat\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586\",\"contentUrl\":\"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586\",\"caption\":\"Kirat\"},\"sameAs\":[\"http:\/\/jassweb.com\"],\"url\":\"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"[Solved] High-performance merging of ordered sets - JassWeb","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/","og_locale":"en_US","og_type":"article","og_title":"[Solved] High-performance merging of ordered sets - JassWeb","og_description":"[ad_1] This is not going to be the fastest data structure & algorithm for your particular purpose I guess, but it may be fast enough. Test it yourself. Note that a std::forward_list or even a std::vector might be faster depending on the actual scenario (-> constant factors in big-O-notation). tmyklebu mentioned another approach in the ... Read more","og_url":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/","og_site_name":"JassWeb","article_published_time":"2022-10-24T08:51:01+00:00","author":"Kirat","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Kirat","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/#article","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/"},"author":{"name":"Kirat","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31"},"headline":"[Solved] High-performance merging of ordered sets","datePublished":"2022-10-24T08:51:01+00:00","mainEntityOfPage":{"@id":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/"},"wordCount":145,"publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"keywords":["algorithm","c++11","performance","real-time-updates","sorting"],"articleSection":["Solved"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/","url":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/","name":"[Solved] High-performance merging of ordered sets - JassWeb","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/#website"},"datePublished":"2022-10-24T08:51:01+00:00","breadcrumb":{"@id":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/jassweb.com\/solved\/solved-high-performance-merging-of-ordered-sets\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/jassweb.com\/solved\/"},{"@type":"ListItem","position":2,"name":"[Solved] High-performance merging of ordered sets"}]},{"@type":"WebSite","@id":"https:\/\/jassweb.com\/solved\/#website","url":"https:\/\/jassweb.com\/solved\/","name":"JassWeb","description":"Build High-quality Websites","publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/jassweb.com\/solved\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/jassweb.com\/solved\/#organization","name":"Jass Web","url":"https:\/\/jassweb.com\/solved\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/","url":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","contentUrl":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","width":693,"height":132,"caption":"Jass Web"},"image":{"@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31","name":"Kirat","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/image\/","url":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586","contentUrl":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586","caption":"Kirat"},"sameAs":["http:\/\/jassweb.com"],"url":"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/"}]}},"_links":{"self":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/17414","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/comments?post=17414"}],"version-history":[{"count":0,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/17414\/revisions"}],"wp:attachment":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/media?parent=17414"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/categories?post=17414"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/tags?post=17414"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}