99 problems in Haskell - Part 1 (Lists)

1. myLast :: [a] -> a

   Find the last element of a list. Assume the list is non empty.

2. myButLast :: [a] -> a

   Find the last but one element of a list. Assume the list has, at least, two elements.

3. elementAt :: Int -> [a] -> a

   Find the $k$-th element of a list. The first element in the list is number 1. Assume the list has, at least, $k$ elements.

4. myLength :: [a] -> Int

   Find the number of elements of a list.

5. myReverse :: [a] -> [a]

   Reverse a list.

6. isPalindrome :: (Eq a) => [a] -> Bool

   Find out whether a list is a palindrome.

7. myFlatten :: [[a]] -> [a]

   Flatten a two-level nested list structure.

8. compress :: (Eq a) => [a] -> [a]

   Eliminate consecutive duplicates of list elements.

9. pack :: (Eq a) => [a] -> [[a]]

   Pack consecutive duplicates of list elements into sublists. If a list contains repeated elements they should be placed in separate sublists.

10. encode :: (Eq a) => [a] -> [(Int, a)]

    Run-length encoding of a list. Consecutive duplicates of elements are encoded as lists $(n,e$) where $n$ is the number of duplicates of the element $e$.

Scoring

Each item scores 10 points.

Problem information

Author: Jordi Petit

Generation: 2026-02-03T16:59:20.681Z

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