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leadersheir's solution

to Trinary in the Julia Track

Published at Feb 04 2021 · 0 comments
Instructions
Test suite
Solution

Convert a trinary number, represented as a string (e.g. '102012'), to its decimal equivalent using first principles.

The program should consider strings specifying an invalid trinary as the value 0.

Trinary numbers contain three symbols: 0, 1, and 2.

The last place in a trinary number is the 1's place. The second to last is the 3's place, the third to last is the 9's place, etc.

# "102012"
    1       0       2       0       1       2    # the number
1*3^5 + 0*3^4 + 2*3^3 + 0*3^2 + 1*3^1 + 2*3^0    # the value
  243 +     0 +    54 +     0 +     3 +     2 =  302

If your language provides a method in the standard library to perform the conversion, pretend it doesn't exist and implement it yourself.

Source

All of Computer Science http://www.wolframalpha.com/input/?i=binary&a=*C.binary-_*MathWorld-

Version compatibility

This exercise has been tested on Julia versions >=1.0.

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

runtests.jl

using Test

include("trinary.jl")

@testset "trinary 1 is decimal 1" begin
    @test trinary_to_decimal("1") == 1
end

@testset "trinary 2 is decimal 2" begin
    @test trinary_to_decimal("2") == 2
end

@testset "trinary 10 is decimal 3" begin
    @test trinary_to_decimal("10") == 3
end

@testset "trinary 11 is decimal 4" begin
    @test trinary_to_decimal("11") == 4
end

@testset "trinary 100 is decimal 9" begin
    @test trinary_to_decimal("100") == 9
end

@testset "trinary 112 is decimal 14" begin
    @test trinary_to_decimal("112") == 14
end

@testset "trinary 222 is decimal 26" begin
    @test trinary_to_decimal("222") == 26
end

@testset "trinary 1122000120 is decimal 32091" begin
    @test trinary_to_decimal("1122000120") == 32091
end

@testset "invalid trinary digits returns 0" begin
    @test trinary_to_decimal("1234") == 0
end

@testset "invalid word as input returns 0" begin
    @test trinary_to_decimal("carrot") == 0
end

@testset "invalid numbers with letters as input returns 0" begin
    @test trinary_to_decimal("0a1b2c") == 0
end
function trinary_to_decimal(str)
    
    nothing ∈ [match(r"[0-2]", i) for i ∈ split(str, "")] && return 0
    
    arr = [parse(Int, i) for i ∈ reverse(split(str, ""))]
    
    for n ∈ 0:length(arr)-1
        arr[n+1] = arr[n+1]*3^n
    end
    
    return sum(arr)
end

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