How to resolve the algorithm 24 game step by step in the PicoLisp programming language

Published on 12 May 2024 09:40 PM
#Picolisp

How to resolve the algorithm 24 game step by step in the PicoLisp programming language

Table of Contents

Problem Statement

The 24 Game tests one's mental arithmetic.

Write a program that randomly chooses and displays four digits, each from 1 ──► 9 (inclusive) with repetitions allowed. The program should prompt for the player to enter an arithmetic expression using just those, and all of those four digits, used exactly once each. The program should check then evaluate the expression. The goal is for the player to enter an expression that (numerically) evaluates to 24.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm 24 game step by step in the PicoLisp programming language

Source code in the picolisp programming language

(load "@lib/frac.l")

(de random4digits ()
   (setq Numbers (make (do 4 (link (rand 1 9)))))
   Numbers )

(de prompt ()
   (prinl
      "^JPlease enter a 'Lisp' expression (integer or fractional math) that equals 24,^J"
      "using (, ), frac, + or f+, - or f-, * or f*, / or f/, and " Numbers "^J"
      "(use each number only once). Enter . to quit." ) )

(de getinput ()
   (setq Expression (catch ’NIL (in NIL (read))))
   Expression )

(de checkexpression (Numbers Expression)
   (make
      (when (diff Numbers (fish num? Expression))
         (link "Not all numbers used.") )
      (when (diff (fish num? Expression) Numbers)
         (link "Using wrong number(s)."))
      (if (sub? "f" (pack Expression))
         (when (diff (fish sym? Expression) '(frac f+ f- f* f/))
            (link "Illegal operator(s). If fractional expression, must use frac, f+, f-, f*, f/ only.") )
         (when (diff (fish sym? Expression) '(+ - * /))
            (link "Using illegal operator(s).") ) ) ) )

(de instructions ()
   (prinl "Example 'Lisp' expression: (- (* 3 9) (+ 1 2))")
   (prinl
      "Example 'Lisp' fractional expression:^J"
      "(f- (f* (frac 3 1)(frac 9 1)) (f+ (frac 1 1)(frac 2 1)))" )
   (prinl
      "Use a fractional expression 'just for fun (as above)' OR if your solution^J"
      "would lose remainder value(s) otherwise (through integer division)." ) )

(de loopuntilquit ()
   (instructions)
   (loop
      (set 'Numbers (random4digits))
      (prompt)
      (set 'Expression (getinput))
      (if (= Expression ".") (prog (prinl "bye!") (bye)))
      (set 'Check (checkexpression Numbers Expression))
      (if (car Check)
         (mapcar prinl Check)
         (prog
            (set 'Evaluated (eval Expression))
            (if (or (= Evaluated 24) (= Evaluated (24 . 1)))
               (prinl "Congratulations!")
               (prinl "That evaluated to " Evaluated " Try again!") ) ) ) ) )

(loopuntilquit)

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