Data commit

Task/Perfect-shuffle/R/perfect-shuffle-1.r

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+wave.shuffle <- function(n) {
+  deck <- 1:n ## create the original deck
+  new.deck <- c(matrix(data = deck, ncol = 2, byrow = TRUE)) ## shuffle the deck once
+  counter <- 1 ## track the number of loops
+  ## defining a loop that shuffles the new deck until identical with the original one
+  ## and in the same time increses the counter with 1 per loop
+  while (!identical(deck, new.deck)) { ## logical condition
+    new.deck <- c(matrix(data = new.deck, ncol = 2, byrow = TRUE)) ## shuffle
+    counter <- counter + 1 ## add 1 to the number of loops
+  }
+  return(counter) ## final result - total number of loops until the condition is met
+}
+test.values <- c(8, 24, 52, 100, 1020, 1024, 10000) ## the set of the test values
+test <- sapply(test.values, wave.shuffle) ## apply the wave.shuffle function on each element
+names(test) <- test.values ## name the result
+test ## print the result out

Task/Perfect-shuffle/R/perfect-shuffle-2.r

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+#A strict reading of the task description says that we need a function that does exactly one shuffle.
+pShuffle <- function(deck)
+{
+  n <- length(deck)#Assumed even (as in task description).
+  shuffled <- array(n)#Maybe not as general as it could be, but the task said to use whatever was convenient.
+  shuffled[seq(from = 1, to = n, by = 2)] <- deck[seq(from = 1, to = n/2, by = 1)]
+  shuffled[seq(from = 2, to = n, by = 2)] <- deck[seq(from = 1 + n/2, to = n, by = 1)]
+  shuffled
+}
+
+task2 <- function(deck)
+{
+  shuffled <- deck
+  count <- 0
+  repeat
+  {
+    shuffled <- pShuffle(shuffled)
+    count <- count + 1
+    if(all(shuffled == deck)) break
+  }
+  cat("It takes", count, "shuffles of a deck of size", length(deck), "to return to the original deck.","\n")
+  invisible(count)#For the unit tests. The task wanted this printed so we only return it invisibly.
+}
+
+#Tests - All done in one line.
+mapply(function(x, y) task2(1:x) == y, c(8, 24, 52, 100, 1020, 1024, 10000), c(3, 11, 8, 30, 1018, 10, 300))