# RogerBW's Blog

 The Weekly Challenge 212: Rearrange by Jumps 16 April 2023 I’ve been doing the Weekly Challenges. The latest involved letter rearrangement and number grouping. (Note that this is open until 16 April 2023.) Task 1: Jumping Letters You are given a word having alphabetic characters only, and a list of positive integers of the same length. Write a script to print the new word generated after jumping forward each letter in the given word by the integer in the list. The given list would have exactly the number as the total alphabets in the given word. Fairly straightforward if we assume ASCII, and since it's a task 1 I did. Easier in languages that have an `enumerate` or `with_index` method, but here's the Perl: ``````sub jumpingletters(\$word, \$jump) { my @s = ''; my \$i = 0; foreach my \$c (split '', \$word) { my \$d = ord(\$c) + \$jump->[\$i] % 26; `````` Because the numbers in `jump` are always positive, we don't need to range-check the low end. `````` if ((\$c le 'Z' && \$d > 90) || \$d > 122) { \$d -= 26; } push @s,chr(\$d); \$i++; } return join('', @s); } `````` Task 2: Rearrange Groups You are given a list of integers and group size greater than zero. Write a script to split the list into equal groups of the given size where integers are in sequential order. If it can’t be done then print -1. As usual, to make things easier across multiple languages some of which have types, I use `[]` (empty list) for a failing return value rather than `-1`. (In Rust I could use a `Result` type, but they only happen in Rust.) Kotlin: ``````fun rearrangegroups(list: List, size: Int): List> { `````` Count the occurrences of each number. `````` var h = mutableMapOf() for (k in list) { if (h.contains(k)) { h[k] = h[k]!! + 1 } else { h[k] = 1 } } var out = ArrayList>() while (true) { `````` Repeatedly look for the minimum number left in the list. If the rearrangement is to be valid, this must be the first of a sequence of length `size`. `````` val m = h.keys.minOrNull()!! val res = (m .. m + size - 1).toList() for (n in res) { `````` Check each term in that sequence. If it's in the list, decrement the count and remove it if the count reaches zero; if it isn't, bail out with a failure state. `````` if (h.contains(n)) { val p = h[n]!! - 1; if (p == 0) { h.remove(n) } else { h[n] = p } } else { return emptyList>() } } `````` Push the sequence onto the output list, and exit when there's nothing left to do. `````` out.add(res) if (h.size == 0) { break } } return out.toList() } `````` 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 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 2022 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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