MovesInSquaredStrings02.md

MovesInSquaredStrings02

Intro

You are given a string of n lines, each substring being n characters long: For example:

s = "abcd\nefgh\nijkl\nmnop"

We will study some transformations of this square of strings.

Clock rotation 180 degrees: rot rot(s) => "ponm\nlkji\nhgfe\ndcba"

selfie_and_rot(s) (or selfieAndRot or selfie-and-rot)

It is initial string + string obtained by clock rotation 180 degrees with dots interspersed in order (hopefully) to better show the rotation when printed.

s = "abcd\nefgh\nijkl\nmnop" --> "abcd....\nefgh....\nijkl....\nmnop....\n....ponm\n....lkji\n....hgfe\n....dcba"

or printed:

|rotation        |selfie_and_rot
|abcd --> ponm   |abcd --> abcd....
|efgh     lkji   |efgh     efgh....
|ijkl     hgfe   |ijkl     ijkl....
|mnop     dcba   |mnop     mnop....
                           ....ponm
                           ....lkji
                           ....hgfe
                           ....dcba

Task

Write these two functions rotand

selfie_and_rot

and

high-order function oper(fct, s) where

• fct is the function of one variable f to apply to the string s (fct will be one of rot, selfie_and_rot)

Examples

s = "abcd\nefgh\nijkl\nmnop"

oper(rot, s) => "ponm\nlkji\nhgfe\ndcba"

oper(selfie_and_rot, s) => "abcd....\nefgh....\nijkl....\nmnop....\n....ponm\n....lkji\n....hgfe\n....dcba"

Notes

The form of the parameter fct in oper changes according to the language.

You can see each form according to the language in "Your test cases".

It could be easier to take these katas from number (I) to number (IV) Forthcoming katas will study other transformations.

Bash Note

The input strings are separated by , instead of \n. The output strings should be separated by \r instead of \n. See "Sample Tests".