Note: This is an attempt at recycling guest271314's permutation question(s) There's an interesting pattern that forms when you find the differences between lexographically sorted permutations of base 10 numbers with ascending unique digits. For example, 123 has permutations: 123 132 213 231 312...

For the purposes of the current challenge to "outline" a word means to surround it successively with its own letters, starting with the last one, and finally to replace the original word in the center with spaces: oooooo onnnno on -> on no onnnno oooooo Task: ...

Challenge Take an input string \$s\$, and split it into words \$w_1, w_2, ..., w_n\$. If the amount of words is odd, then return \$s\$. Otherwise, for each word: Take the second last letter, and swap it with the first letter keeping capitalization positions. So GolF becomes LogF. Now check if t...

Given a positive integer, write it as the sum of items, where each item is in \$\{kt|k\in{1,9,81},t\in{1,2,3,...,64}\}\$. How many items at least are used? Shortest code win. Samples: Input Output Method 1 1 1 2 1 2 64 1 64 65 2 64+1 72 1 72 343 ...

Matlab has a useful command for visualizing data: plot. It draws data points using "markers" in 2-D space, connecting them with lines; however, for this challenge, let's ignore the lines and use only markers. In fact, only one marker. Input: one of Matlab's marker symbols: . o x + * s d v ^ < > ...

Given a non-empty rectangular array of integers from 0 to 9, output the amount of cells that equal 8 and do not have a neighbour cell equal to 8. Neighbouring is here understood in the Moore sense, that is, including diagonals. So each cell has 8 neighbours, except for cells on the edges of the a...