Bracket Inc. wants to ship out new products using their excess brackets. They have tasked you with generating every possible assortment of brackets for some n brackets where the brackets will match
- A bracket match is an opening and closing version of the same kind of bracket beside each other
()
- If a bracket matches then outer brackets can also match
(())
- n will be an even number
- The valid brackets are ()[]{}
For example for n = 4 the options are
- ()()
- (())
- [][]
- [[]]
- {}{}
- {{}}
- []()
- ()[]
- (){}
- {}()
- []{}
- {}[]
- ({})
- {()}
- ([])
- [()]
- {[]}
- [{}]
You must accept n as a command line argument (entered when your app is ran) and print out all of the matches, one per line
(It will be called like node main.js 4
or however else to run apps in your language)
You can use the solution tester in this post to test you followed the correct format https://programming.dev/post/1805174
Any programming language may be used. 2 points will be given if you pass all the test cases with 1 bonus point going to whoevers performs the quickest and 1 for whoever can get the least amount of characters
To submit put the code and the language you used below
Older solution that doesn’t work quite right
spoiler
This time I did it in JavaScript. Overall, it solves it in a reasonable amount of time up to n = 16, but won’t at n = 18 and up.
const BRACKETS = [['(', ')'], ['[', ']'], ['{', '}']]; function brackets(n) { if (n === 1) return ['()', '[]', '{}']; let o = {}; function addBracket(s) { BRACKETS.forEach(b => { o[b[0] + b[1] + s] = true; o[b[0] + s + b[1]] = true; o[s + b[0] + b[1]] = true; }); } brackets(n - 1).forEach(addBracket); return Object.keys(o); } brackets(Number(process.argv[2]) / 2).forEach(v => console.log(v));
I don’t feel experienced enough with data structures and algorithms to make this more efficient. I really just started learning this stuff and don’t have a great grasp of it yet. I could of probably used a set to save some lines instead of a hashmap, but eh, its probably slightly faster because I went the hashmap route to get rid of duplicates.
I revised it because I was pointed out I missed an aspect of the problem. This is in JavaScript
const BRACKETS = ['()', '[]', '{}']; function brackets(n) { if (n === 0) return ['']; let strings = brackets(n - 1); let o = {}; for (let s of strings) { for (let i = 0; brackets.length >= i; i++) { for (let b of BRACKETS) { o[s.slice(0, i) + b + s.slice(i)] = true; } } } return Object.keys(o); } brackets(Number(process.argv[2]) / 2).forEach(v => console.log(v));
Interesting approach, but from my understanding of the code, it doesn’t generate matches like
[()][()]
. I could be wrong, but I don’t see how you can get that by prepending, appending, and enclosing just()
,[]
, and/or{}
.I’m also assuming that
[()][()]
is supposed to be one of the results for n = 8. At least two others here seem to have made that assumption, and I believe it’s consistent with the previous challenge. Would be nice to have some clarification on this, though.You know, you are right. I overlooked the idea of there being multiple nests. That complicates things.
I could probably revise the current method, but build different n sized clusters through recursion, then just mix them.
Or, maybe just an insertion based one, placing a full bracket at every position in the string. That probably would be faster than the previous idea.
I guess I’ll work on that tomorrow.I ended up updating it now.
Thanks for the heads up.