# RogerBW's Blog

 The Weekly Challenge 195: Frequently Special 18 December 2022 I’ve been doing the Weekly Challenges. The latest involved integer filtering. (Note that this closes today.) Task 1: Special Integers You are given a positive integer, \$n > 0. Write a script to print the count of all special integers between 1 and \$n. An integer is special when all of its digits are unique. Therefore: convert to string, check for uniqueness of characters. (Could have done it as a repeated mod10, but I felt stringy.) For the uniqueness test, I incremented hashes where that was easy, or used sets where they were readily available. PostScript: ``````/specialintegers { 4 dict begin /n exch def /o 0 def `````` For each candidate number: `````` 1 1 n { /f 0 dict def /s true def `````` Convert it to a string and iterate over the characters. `````` dup log cvi 1 add string cvs { /c exch def `````` If we've seen it before, mark as non-special and bail out. `````` f c known { /s false def exit } { `````` Otherwise record it. `````` f c true put } ifelse } forall `````` If it's special, increment the output count. `````` s { /o o 1 add def } if } for o end } bind def `````` Task 2: Most Frequent Even You are given a list of numbers, `@list`. Write a script to find most frequent even numbers in the list. In case you get more than one even numbers then return the smallest even integer. For all other case, return -1. Perl: ``````sub mostfrequenteven(\$l) { my %f; `````` Filter for evenness and build a frequency table. `````` foreach my \$n (@{\$l}) { if (\$n % 2 == 0) { \$f{\$n}++; } } if (scalar %f > 0) { `````` Get the maximum frequency, and sort the keys that have that freqency. The first one is the lowest number. `````` my \$m = max(values %f); my @l = grep {\$f{\$_} == \$m} keys %f; @l = sort @l; return \$l[0]; } else { `````` If there were no even numbers, return -1. `````` return -1; } } `````` Full code on github. Comments on this post are now closed. If you have particular grounds for adding a late comment, comment on a more recent post quoting the URL of this one. Search 10 per page 20 per page 50 per page 100 per page Archive Tags 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s 2000s 2010s 3d printing action advent of code aeronautics aikakirja anecdote animation anime army astronomy audio audio tech aviation base commerce battletech beer boardgaming book of the week bookmonth chain of command children chris chronicle church of no redeeming virtues cold war comedy computing contemporary cornish smuggler cosmic encounter coup covid-19 crime crystal cthulhu eternal cycling dead of winter doctor who documentary drama driving drone ecchi economics en garde espionage essen 2015 essen 2016 essen 2017 essen 2018 essen 2019 essen 2022 essen 2023 existential risk falklands war fandom fanfic fantasy feminism film firefly first world war flash point flight simulation food garmin drive gazebo genesys geocaching geodata gin gkp gurps gurps 101 gus harpoon historical history horror hugo 2014 hugo 2015 hugo 2016 hugo 2017 hugo 2018 hugo 2019 hugo 2020 hugo 2021 hugo 2022 hugo 2023 hugo 2024 hugo-nebula reread in brief avoid instrumented life javascript julian simpson julie enfield kickstarter kotlin learn to play leaving earth linux liquor lovecraftiana lua mecha men with beards mpd museum music mystery naval noir non-fiction one for the brow opera parody paul temple perl perl weekly challenge photography podcast politics postscript powers prediction privacy project woolsack pyracantha python quantum rail raku ranting raspberry pi reading reading boardgames social real life restaurant reviews romance rpg a day rpgs ruby rust scala science fiction scythe second world war security shipwreck simutrans smartphone south atlantic war squaddies stationery steampunk stuarts suburbia superheroes suspense television the resistance the weekly challenge thirsty meeples thriller tin soldier torg toys trailers travel type 26 type 31 type 45 vietnam war war wargaming weather wives and sweethearts writing about writing x-wing young adult Special All book reviews, All film reviews
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