Modular•12mo ago

Refactoring from DynamicVector to a different data structure?

I'm currently teaching myself Mojo by porting the solutions to Codewars katas in Python over to the new language. The "safecracker" problem asks you to write a function that returns a tuple of three integers. My Python solution used the tuple type. My Mojo solution uses DynamicVector in place of tuple. There must be a better way to do it than that, surely? I'm having difficulty with the official docs (skill issue on my part). Suggestions welcome. Help appreciated.

from utils.vector import DynamicVector

fn safecracker(start:Int, incs:DynamicVector[Int]) -> DynamicVector[Int]:
    var vec = DynamicVector[Int](3)
    vec.push_back((start - incs[0]) % 100)
    vec.push_back((vec[0] + incs[1]) % 100)
    vec.push_back((vec[1] - incs[2]) % 100)
    return vec

fn main():
    var vec0 = DynamicVector[Int](3)
    vec0.push_back(54)
    vec0.push_back(48)
    vec0.push_back(77)
    let result = safecracker(96, vec0)
    print(result[0], result[1], result[2])

from utils.vector import DynamicVector

fn safecracker(start:Int, incs:DynamicVector[Int]) -> DynamicVector[Int]:
    var vec = DynamicVector[Int](3)
    vec.push_back((start - incs[0]) % 100)
    vec.push_back((vec[0] + incs[1]) % 100)
    vec.push_back((vec[1] - incs[2]) % 100)
    return vec

fn main():
    var vec0 = DynamicVector[Int](3)
    vec0.push_back(54)
    vec0.push_back(48)
    vec0.push_back(77)
    let result = safecracker(96, vec0)
    print(result[0], result[1], result[2])

2 Replies

Stole•12mo ago

DynamicVector's really for containers that change size a lot. Mojo has a Tuple type which has similar functionality to Python's tuple, and you can see it here: https://docs.modular.com/mojo/stdlib/builtin/tuple.html. However, I think that StaticTuple (https://docs.modular.com/mojo/stdlib/utils/static_tuple.html) actually could be better suited here, since it's for containers whose sizes don't change, and with homogenous types (Tuple can handle different types, which we don't need, and makes it a little more annoying to access elements). Something like this is likely what you're looking for.

from utils.static_tuple import StaticTuple
alias Tuple3I = StaticTuple[3, Int]

fn safecracker(start: Int, incs: Tuple3I) -> Tuple3I:
    var vec = Tuple3I()
    vec[0] = (start - incs[0]) % 100
    vec[1] = (vec[0] + incs[1]) % 100
    vec[2] = (vec[1] - incs[2]) % 100
    return vec

fn main():
    let vec0 = Tuple3I(54, 48, 77)
    let result = safecracker(96, vec0)
    print(result[0], result[1], result[2])

from utils.static_tuple import StaticTuple
alias Tuple3I = StaticTuple[3, Int]

fn safecracker(start: Int, incs: Tuple3I) -> Tuple3I:
    var vec = Tuple3I()
    vec[0] = (start - incs[0]) % 100
    vec[1] = (vec[0] + incs[1]) % 100
    vec[2] = (vec[1] - incs[2]) % 100
    return vec

fn main():
    let vec0 = Tuple3I(54, 48, 77)
    let result = safecracker(96, vec0)
    print(result[0], result[1], result[2])

Sammi Turner•12mo ago

Perfect answer. Thank you!

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Refactoring from DynamicVector to a different data structure?