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svigneau's solution

to Secret Handshake in the R Track

Published at Jan 03 2021 · 0 comments
Instructions
Test suite
Solution

There are 10 types of people in the world: Those who understand binary, and those who don't.

You and your fellow cohort of those in the "know" when it comes to binary decide to come up with a secret "handshake".

``````1 = wink
1000 = jump

10000 = Reverse the order of the operations in the secret handshake.
``````

Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.

Here's a couple of examples:

Given the input 3, the function would return the array ["wink", "double blink"] because 3 is 11 in binary.

Given the input 19, the function would return the array ["double blink", "wink"] because 19 is 10011 in binary. Notice that the addition of 16 (10000 in binary) has caused the array to be reversed.

Installation

See this guide for instructions on how to setup your local R environment.

In each problem folder, there is a file named `<exercise_name>.R` containing a function that returns a `NULL` value. Place your implementation inside the body of the function.

How to run tests

Inside of RStudio, simply execute the `test_<exercise_name>.R` script. This can be conveniently done with testthat's `auto_test` function. Because exercism code and tests are in the same folder, use this same path for both `code_path` and `test_path` parameters. On the command-line, you can also run `Rscript test_<exercise_name>.R`.

Source

Bert, in Mary Poppins http://www.imdb.com/title/tt0058331/quotes/qt0437047

Submitting Incomplete Solutions

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

test_secret-handshake.R

``````source("./secret-handshake.R")
library(testthat)

context("secret handshake")

test_that("wink for 1", {
expect_equal(handshake(1), c("wink"))
})

})

test_that("close your eyes for 100", {
})

test_that("jump for 1000", {
expect_equal(handshake(8), c("jump"))
})

test_that("combine two actions", {
})

test_that("reverse two actions", {
})

test_that("reversing one action gives the same action", {
expect_equal(handshake(24), c("jump"))
})

test_that("reversing no actions still gives no actions", {
expect_equal(handshake(16), c())
})

test_that("all possible actions", {
expect_equal(handshake(15),
})

test_that("reverse all possible actions", {
expect_equal(handshake(31),
})

test_that("do nothing for zero", {
expect_equal(handshake(0), c())
})

test_that("do nothing if lower 5 bits not set", {
expect_equal(handshake(32), c())
})

message("All tests passed for exercise: secret-handshake")``````
``````handshake <- function(n) {

# determine handshake actions
handshake <- c()

while(length(actions) > 0) {
if (n %% 2 == 1) {
handshake <- c(handshake, actions[1])
}
actions <- actions[-1]
n <- n %/% 2
}

# determine if handshake should be reversed
if (n %% 2 == 1) {
handshake <- rev(handshake)
}

handshake
}``````