On a programming forum I have found a small programming problem about guessing numbers. I have implemented its solutions this morning using Haskell, only to practice a little some Haskell programming. The problem is quite easy to solve. I have used lists instead of arithmetic operations to reach the final number without errors, avoiding user mistakes.
we all know the classic «guessing game» with higher or lower prompts. lets do a role reversal; you create a program that will guess numbers between 1-100, and respond appropriately based on whether users say that the number is too high or too low. Try to make a program that can guess your number based on user input and great code!
And here is my solution — where it has some validations to avoid the wrong input.
module Main where
import System.IO.Unsafe
import Text.Printf
promptOptions :: String
promptOptions = "[Yes (y), Higher (h), Lower (l)]"
queryNumber :: Int -> String
queryNumber n = printf "Is your number %s? %s"
( show n ) promptOptions
printNumber :: Int -> String
printNumber n = printf "Your number is %s"
( show n )
promptNumber :: Int -> IO String
promptNumber n = putStrLn ( queryNumber n ) >> getLine
reduceList :: String -> Int -> [Int] -> [Int]
reduceList m n xs | m == "h" = filter (> n) xs
| m == "l" = filter (< n) xs
| m == "y" = [n]
| otherwise = xs
searchNumber :: [Int] -> IO ()
searchNumber m = let ln = length m `div` 2
nm = m !! ln
mn = unsafePerformIO $ promptNumber nm
rs = reduceList mn nm m
in case length rs of
1 -> putStrLn $ printNumber $ head rs
_ -> searchNumber rs
main :: IO ()
main = do putStrLn "Is your number odd (o) or even (e)?"
x <- getLine
case x of
"e" -> searchNumber $ filter odd [ 1 .. 100 ]
"o" -> searchNumber $ filter even [ 1 .. 100 ]
_ -> main
To compile this program with GHC, try ghc --make prog.hs -o prog, also it works with runghc prog.hs.
Solution in C#:
using System; namespace GuessingNumber { class MainClass { public static void Main (string[] args) { var min = 1; var max = 100; while (min != max) { var myguess = (max + min) / 2; Console.WriteLine ( "nIs your number {0}? Yes (y){1}{2}", myguess, (myguess min) ? ", Lower (l)" : string.Empty); var response = Console.Read (); if (response == (int) 'y') { Console.WriteLine ("nDone!"); return; } if (myguess min && response == (int) 'l') max = Math.Max (myguess - 1, min); } Console.WriteLine ("nYour number is {0}", min); } } }