# RogerBW's Blog

 The Weekly Challenge 196: Pattern and Range 25 December 2022 I’ve been doing the Weekly Challenges. The latest involved looking for patterns in arrays. (Note that this closes today. Merry Christmas!) Task 1: Pattern 132 You are given a list of integers, `@list`. Write a script to find out subsequence that respect Pattern 132. Return empty array if none found. Pattern 132 is a sequence (a[i], a[j], a[k]) such that `i < j < k` and `a[i] < a[k] < a[j]`. The obvious answer here is nested loops and I see no reason not to be obvious. Some languages don't like breaking out of loops, but Raku isn't one of them. ``````sub pattern132(@l) { my @o = []; OLOOP: for (0..@l.elems-3) -> \$a { for (\$a+1..@l.elems-2) -> \$b { if (@l[\$a] < @l[\$b]) { for (\$b+1..@l.elems-1) -> \$c { if (@l[\$b] > @l[\$c] && @l[\$a] < @l[\$c]) { @o = [@l[\$a], @l[\$b], @l[\$c]]; last OLOOP; } } } } } return @o; } `````` Task 2: Range List You are given a sorted unique integer array, @array. Write a script to find all possible Number Range i.e [x, y] represent range all integers from x and y (both inclusive). (Each subsequence of two or more contiguous integers) The most fiddly bit here was skipping one entry in a list, and that's not even technically necessary. Rust: ``````fn rangelist(l: Vec) -> Vec> { let mut o = Vec::new(); let mut start = l[0]; let mut prev = start; `````` For each entry in the list except the first: `````` for &v in l.iter().skip(1) { `````` If current isn't one more than previous, the previous one might have been an end of sequence. `````` if v != prev + 1 { `````` Was `prev` (set for every entry) greater than `start` (set only for new sequences)? Then it was an end of sequence; note it. `````` if prev > start { o.push(vec![start, prev]); } `````` Whether it was nor not, set start to current as it might be the beginning of a new sequence. `````` start = v; } `````` Whether or not we did any of that, set `prev` ready for the next pass round the loop. `````` prev = v; } `````` And at the end, log any sequence that was still ongoing. (Perhaps it would be cleaner to push a dummy value on the end of the list.) `````` if prev > start { o.push(vec![start, prev]); } o } `````` 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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