Kids shuffling cards

Question

Shuffling a deck of cards is hard for kids, so they must figure out ways to get a reasonable well shuffled deck as simply as possible.

One way to do this that gives reasonably good results is:

1. Take the top card out and insert it a random place in the deck
2. Take the bottom card out and insert it in a random place in the deck
3. Continue until you believe it's good enough.

Note that you shall never insert a card in the top or bottom spot, it should be placed somewhere in the deck.

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Instead of shuffling cards, we'll shuffle alphanumerical characters: 0-9, A-J, a-j, q-z and Q-Z.

Start with the string shown below and shuffle the characters the way it's described above. You can choose if you want to continue shuffling infinitely or shuffle the cards 100 rounds (100 cards from the top and 100 cards from the bottom).

0123456789abcdefghijqrstuvwxyzABCDEFGHIJQRSTUVWXYZ

The challenge is to display the characters being shuffled. Each "shuffle" (take out and insert card) shall take between 0.25 and 0.35 seconds.

The gif below shows an example output:

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This is code-golf so the shortest code in bytes wins.

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_{"Why don't you have a-t instead of a-j, q-z?" Because this shall illustrate suits of cards, not just characters. And yes, there are 5 suits.}

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Note: I have decided to stop using the check mark on code-golf-challenges. Relevant meta posts here and here.

Answer 1

JavaScript (ES6), 192 188 185 bytes

document.write('<pre id=o>')
s='ABCDEFGHIJQRSTUVWXYZ'
a=[0,...123456789+s.toLowerCase()+s]
setInterval('o.innerText=a.join``;a.splice(Math.random(s^=1)*48+1,0,s?a.pop():a.shift())',250)

Edit: Saved 4 bytes thanks to @L.Serné. Saved 3 bytes thanks to @Arnauld.

Answer 2

MATL, 62 58 56 bytes

2 Bytes saved thanks to @Luis

4Y2'A':'J'tk'Q':'Z'tk&h`48YrQJh&)@o?l&)wb}wO&)]&htD3&XxT

This version will run indefinitely. Try the online demo at MATL Online, an experimental online interpreter that supports dynamic output. This will run for 30 seconds (a hard limit imposed by the online version) if it isn't killed first.

Explanation

4Y2     % Predefined literal for the characters '0'...'9'
'A':'J' % Create an array of the characters 'A'...'J'
tk      % Duplicate and make lowercase
'Q':'Z' % Create an array of the characters 'Q'...'Z'
tk      % Duplicate and make lowercase
&h      % Horizontally concatenate everything
`       % Do...while loop
  48YrQ % Determine a random integer between 2 and 49 
  Jh&)  % Split the string at the selected location
  @o?   % If this is an odd time through the loop
    l&) % Grab the first character
    wb  % Move it to the middle of the stack of three strings
  }     % Else...
    wO&)% Grab the last character and move it to the middle of the stack
  ]     % End of if statment
  &h    % Horizontally concatenate all strings on the stack
  tD    % Duplicate and display the current string
  3&Xx  % Pause for 0.3 seconds and clear the display
  T     % Push a literal TRUE to the stack to make this an infinite loop
        % Implicit end of while loop

Answer 3

Python 3, 199 196 192 186 bytes

Saved 4 bytes thanks to TuukkaX, and 6 bytes thanks to FlipTack!

import time,random
s="abcdefghijqrstuvwxyz";s="0123456789"+s+s.upper()
f=0
while 1:print(end="\r"+s);time.sleep(.3);s,e=s[1^f:50-f],s[f and-1];i=random.randint(1,49);s=s[:i]+e+s[i:];f^=1

Uses Python 3's print function to suppress newline, shorter than Python 2's sys.stdout.write.

Uses a flip-flop variable to switch between moving the top and the bottom cards.

Ungolfed:

from random import randint
from time import sleep

string = "abcdefghijqrstuvwxyz"
string = "0123456789" + string + string.upper()
flip_flop = 0
while True:
    print("\r"+string,end="")
    sleep(0.3)
    string,char = string[not flip_flop:50-flip_flop], string[flip_flop and -1]
    position = randint(1,49)
    string = string[:position] + char + string[position:]
    f = not f

Answer 4

Perl, 117 bytes

@F=(0..9,a..j,"q"..z,A..J,Q..Z);{print"\r",@F;splice@F,++$|+rand(@F-2),0,++$v%2?shift@F:pop@F;select$,,$,,$,,.3;redo}

To run it:

perl -e '@F=(0..9,a..j,"q"..z,A..J,Q..Z);{print"\r",@F;splice@F,++$|+rand(@F-2),0,++$v%2?shift@F:pop@F;select$,,$,,$,,.3;redo}'

Explanations:
-@F=(0..9,a..j,"q"..z,A..J,Q..Z) creates the initial deck, and stores it in @F.
-{...;redo} executes ... forever.
-splice@F,++$|+rand(@F-2),0,++$v%2?shift@F:pop@F alternatively remove the first/last element from the deck and insert in at a random position (while incrementing $|, so the prints aren't buffered),
- print"\r",@F prints the deck,
- select$,,$,,$,,.3 sleeps for 0.3 seconds (Perl's sleep can't sleep for less than 1 second),

Answer 5

C, 290 285 bytes

#include<stdio.h>
#include<time.h>
#define S(s,a,b){int p=rand()%48+1;clock_t c=clock()+300;while(c>clock());int x=d[s];for(int i=s;i a p;)d[i b]=d[i];d[p]=x;printf(d);}
main(){char d[]="0123456789abcdefghijqrstuvwxyzABCDEFGHIJQRSTUVWXYZ\r";srand(time(0));for(;;){S(0,<,++)S(49,>,--)}}

Ungolfed:

#include<stdio.h> // variadic(printf) functions without a valid prototype = UB
#include<time.h>  // required for the implementation-defined clock_t type
// note that <stdlib.h> isnt required for srand()/rand() because they are
//  validly declared implicitly
#define S(s,a,b) // macro function
{
    int p=rand()%48+1;     // get a random position within the array
    clock_t c=clock()+300; // get the time 300 milliseconds from now
    while(c>clock());      // wait for that time
    int x=d[s];            // save the s'th character in a tempvar
    for(int i=s;i a p;)    // shift everything in the array from p
        d[i b]=d[i];       // a determines the comparison: </>
                           // b determines the operation: ++/--
    d[p]=x;                // put the tempvar in its new position
    printf(d);             // print the modified string
} // note: the \r at the end makes it so the next printf overwrites it

main() // main entry point
{      // deck to shuffle below
    char d[]="0123456789abcdefghijqrstuvwxyzABCDEFGHIJQRSTUVWXYZ\r";
    srand(time(0)); // seed the random number generator
    for(;;)         // infinite loop
    {
        S(0,<,++)   // shuffle from the start of the deck
        S(49,>,--)  // shuffle from the end of the deck
    }
}

Answer 6

Ruby (138 119 Bytes)

f=0;a=[*0..9,*?a..?j,*?q..?z,*?A..?J,*?Q..?Z];loop{$><<a*''+?\r;a.insert(rand(48),f>0? a.shift : a.pop);f^=1;sleep 0.3}

Not as short as @PaulPrestidge but at least I understand it.. Also great to learn that ruby is like a endless tunnel of awesome!

Answer 7

Swift, 288 bytes

import Darwin
var o=Array("0123456789abcdefghijqrstuvwxyzABCDEFGHIJQRSTUVWXYZ".characters)
while true{
print(String(o),terminator:"\r")
fflush(__stdoutp);{o.insert(o.removeLast(),at:$0())
o.insert(o.removeFirst(),at:$0()+1)}({Int(arc4random_uniform(UInt32(o.count-1)))})
usleep(300000)
}

Golfing in Swift is always a challenge, as one of its selling points is expressiveness.

Answer 8

Noodel, noncompeting 41 bytes

"Q…Z"A…J"q…z"a…j"0…9⁵⁺ḷçṛ47⁺1ɱɲOṃḃɲ49ḅṙḍq

Try it:)

How It Works

"Q…Z"A…J"q…z"a…j"0…9⁵⁺                    # Creates the string literal to be shuffled.
                      ḷçṛ47⁺1ɱɲO      ṙḍq # The main "infinite" loop that applies the animation.
                                ṃḃɲ49ḅ    # Sub-loop that acts like an if-statement that only runs every odd iteration of the loop.

"Q…Z                                      # Pushes the string literal "QRSTUVWXYZ".
    "A…J                                  # Pushes the string literal "ABCDEFGHIJ".
        "q…z                              # Pushes the string literal "qrstuvwxyz".
            "a…j                          # Pushes the string literal "abcdefghij".
                "0…9                      # Pushes the string literal "0123456789".
                    ⁵⁺                    # Add the five strings on the stack to make one string.
                      ḷ                   # Unconditionally loop the following code.
                       ç                  # Copy what is on the top of the stack, clear the screen, and then print the copy.
                        ṛ47               # Create a random integer from 0 to 47.
                           ⁺1             # Increment the number to get 1 - 48 such that will not be the top or bottom of the deck.
                             ɱ            # Push the number of times that the unconditional loop has ran.
                              ɲO          # Consume the counter and push on zero if is even and one if is odd.
                                ṃ         # Conditional loop that only passes if the top of the stack is truthy (if the counter is odd).
                                 ḃ        # Throws away the top of the stack.
                                  ɲ49     # Pushes the literal 49 in order to represent the top of the deck.
                                     ḅ    # Ends the conditional loop.
                                      ṙ   # Relocate an element in the string by using the two numbers on the stack (either 0 or 49 to the random number).
                                       ḍq # Delay for a quarter of second. (End of unconditional loop)

<div id="noodel" code='"Q…Z"A…J"q…z"a…j"0…9⁵⁺ḷçṛ47⁺1ɱɲOṃḃɲ49ḅṙḍq' input="" cols="50" rows="2"></div>

<script src="https://tkellehe.github.io/noodel/release/noodel-0.0.js"></script>
<script src="https://tkellehe.github.io/noodel/ppcg.min.js"></script>

Answer 9

Ruby, 111 101 characters

s=[*0..9,*?a..?j,*?q..?z,*?A..?J,*?Q..?Z,?\r]*''
loop{$><<s;s[1+rand(48),0]=s.slice!$.^=-2;sleep 0.3}

Loops infinitely.

Answer 10

bash, 170 bytes

r(){((r=RANDOM%48+1));echo -n $c^;sleep .3;}
c=0123456789abcdefghijqrstuvwxyzABCDEFGHIJQRSTUVWXYZ
while r
do
c=${c:1:r}${c:0:1}${c:r+1}
r
c=${c:0:r}${c:49}${c:r:-1}
done

here '^' (on the first line) represents ctrl-m: entered on the command-line as ctrl-v enter or in an editor according to how your editor works (assuming your editor works)