More Codington Crescent

Question

Who's up for a second attempt?

If you've ever listened to the radio program "I'm sorry, I haven't a clue", then you've probably heard of the game called "Mornington Crescent". For those who haven't, it's a game where players name random stations on the London Underground network. The first person to name "Mornington Crescent" wins the game.₁

Very much like last time, I present to you another game of Codington Crescent.

The Challenge

The winner of this challenge is the first person to post a working program that, given a variable-sized list of positive integers, returns the average (arithmetic mean) of said list. The list will not be empty and will always have at least one item. Input and output can be given in any reasonable and convenient format

Test Cases

[150, 541, 168, 225, 65, 191, 964, 283, 825, 5, 802, 426, 45, 326, 22, 619, 281] => 349.29411764705884
[874, 33, 423, 36, 1000, 255, 345, 902, 700, 141, 916, 959, 222, 246, 96] => 476.53333333333336
[567, 868, 680, 121, 574, 391, 233, 39, 764, 499, 455, 684, 742, 117, 376] => 474.0
[177, 372, 778, 709, 474, 796, 840, 742] => 611.0
[181, 751, 940, 782, 727, 756, 541, 762, 677, 751, 719] => 689.7272727272727
[47, 804, 782, 231, 170] => 406.8
[315, 972] => 643.5
[679, 727] => 703.0
[859, 229, 363, 468, 103, 104, 570, 772, 83, 693, 898, 672, 306, 733, 189, 717, 231] => 470.0
[228, 839] => 533.5
[395, 622, 760, 820, 70, 814, 797, 202, 277, 663, 93, 218, 564, 735] => 502.14285714285717
[724, 631, 932, 333, 605, 880, 670, 468, 703, 744, 680, 28] => 616.5
[950, 733, 305, 178, 995] => 632.2
[762, 506, 553, 284, 499, 694, 665, 998, 576, 504, 123, 658, 943, 385, 354, 732] => 577.25
[151, 919, 514, 721, 426, 333, 808, 514] => 548.25
[995] => 995.0
[891, 243, 42, 968, 458, 372, 301, 269, 559, 394, 980, 372, 804, 429, 738] => 521.3333333333334
[147, 473, 632] => 417.3333333333333
[105, 483, 225, 541, 684, 456, 328] => 403.14285714285717
[311, 1, 770, 417, 910, 185, 375, 631, 226, 266, 609] => 427.3636363636364

Test case generator

The Rules

1. Each player has their own program that they will add/change characters. This is termed their running program.

In this way, the only answer-chaining aspect is the rules. Everyone uses their own running program. No one shares a program at all

2. Each answer (a turn) has to obey source restrictions defined by previous answers. These are called rules. Each variant lasts for 5 turns. Rules are in the form of restricted-source restrictions.

3. Running programs can change languages between turns.

4. Answerers (players) can either add, change or remove (but only one of the options) as many characters of their running program per turn as they like. Alternatively, they can choose to "pass" (more scientifically, farkle), adding no new rules, and still counting as a turn. This may be the only choice if rules conflict with each other. The turn count is still incremented and is to be posted. Pro tip: You probably might want to mark it community wiki because it doesn't add much.

5. At the end of each turn, the player declares a new rule that will span the next 5 turns. Rules must be objective, and a TIO verification program is highly recommended. Also, rules have to be able to be applied to every language (e.g. Programs must not error using Python 3.4.2 isn't a valid rule).

6. Play continues until a running program achieves the target result.

7. If a turn hasn't been taken for a week, then an implicit farkle will occur. You can always take a turn after an implicit farkle, as it counts as a turn (think of it as the Community user's turn).

Starting Rules

As to kick off the game, the first 5 turns must follow these rules:

1. Turns may not accomplish the end goal
2. Minimum program length is 10 bytes

Permanent Rules

Last time, it was noted that the following rules suited better as a permanent rule rather than 5-turn rules:

3. Running programs must be irreducible. Irreducible in this case means that the program doesn't produce the output of the whole program if characters from the whole program are removed. Ie. There does not exist a program that has the default same output that can be constructed by removing characters from the original program.)

4. A program cannot win within 5 turns of its first appearance

Example Rules

These are purely examples of what you could add as rules to the challenge. They do not apply unless someone decides to use them.

• The first and last character of the running program must be a space
• Running programs must have an even amount of bytes
• Running programs must not be more than 30 bytes

Extra Answer Chaining Rules

• You cannot answer twice in a row. Someone else needs to answer before you have another go.
• Languages need to be on Try It Online to be valid answers.

Pro-tip: sort by oldest for a more cohesive flow of answers

_{1 The original game of Mornington Crescent doesn't really have rules... It's more of an activity that looks like it's a complicated game.}

Answer Template

# [Language], turn number [your turn]

    <code>

[Try it online link]
[prev answer link] 

## Rules

- Rule (n turns left)
- Rule (n turns left)
- Rule (n turns left)

Answer 1

05AB1E, turn 3

$XY~sDOsg/*+

Try it online!

^{(How do I link to previous answer?)}

Boy do I love Code Golf!

Explanation

$               # Push 1 and input
 X              # Push 1
  Y             # Push 2
   ~            # Converts 1 and 2 to 3
    s           # Swap to get implicit input
     D          # Duplicate
      O         # Sum the list
       s        # Swap top 2 values and gets the preserved list.
        g       # Push the length of the list.
         /      # Push the quotient of sum and length
          *     # Multiply with 3
           +    # Add with one

Current rules

• Turns may not accomplish the end goal - Prints the triple the average plus one (2 turns left!)
• Minimum program length is 10 bytes (3 turns left) - Length of the program is 12 bytes (2 turns left!)
• Programs must contain the ~ character - The character is supposed to push the bitwise OR of 1 and 2 (3 turns left!)
• Programs must have an average byte value of less than or equal to 80 - The average byte value of the program is 79.25 (4 turns left!)

The new rule

Drumroll

---

The program must include 5-10 non-alphanumeric characters (5 turns left!)

Answer 2

Io, 20 bytes

Returns the average+1.

method(~,~average+1)

Try it online!

Rules

the first 5 turns must follow these rules:

• Turns may not accomplish the end goal
• Minimum program length is 10 bytes

this applies for all running programs:

• Running programs must be irreducible. Irreducible in this case means that the program doesn't produce the output of the whole program if characters from the whole program are removed. Ie. There does not exist a program that has the default same output that can be constructed by removing characters from the original program.)

• A program cannot win within 5 turns of its first appearance

New rule:

• Programs must contain the ~ character

Answer 3

Python 3, 23 bytes, turn 2

lambda l:sum(l)/~len(l)

Try it online!

Input as a list of floats; outputs as a float.

Rules

Permanent rules:

• Running programs must be irreducible. Irreducible in this case means that the program doesn't produce the output of the whole program if characters from the whole program are removed. Ie. There does not exist a program that has the default same output that can be constructed by removing characters from the original program.)

• A program cannot win within 5 turns of its first appearance

Current rules:

• Turns may not accomplish the end goal (3 turns left)
• Minimum program length is 10 bytes (3 turns left)
• Programs must contain the ~ character (4 turns left)

My new rule:

• Programs must have an average byte value of less than or equal to 80. (verifier)

Answer 4

Befunge-98 (PyFunge), 13 bytes, turn 5

(turn 4 was an implicit farkle)

"PDPF"4(~FP@

This answer is far from winning, but I'm including some characters an average program in this language will likely need, and keeping the challenge alive.

Try it online!

Previous answer

Rules:

• Programs may not accomplish the end goal (last turn)
• Minimum program length is 10 bytes (last turn)
• Programs must contain the ~ character (1 turn left)
• Programs must have an average byte value of less than or equal to 80. (2 turns left)
• The program must include 5-10 non-alphanumeric characters (3 turns left!)
• Programs may not contain 2 consecutive lowercase letters (5 turns left)