Sorted:

CodeSignal Interview – isCryptSolution

CodeSignal Interview – sudoku2

CodeSignal Interview – firstNotRepeatingCharacter

CodeSignal Interview – firstDuplicate

CodeSignal Interview – rotateImage

CodeSignal Arcade – arrayMaximalAdjacentDifference

CodeSignal Arcade – areEquallyStrong

CodeSignal Arcade – palindromeRearranging

CodeSignal Arcade – Are Similar?

CodeSignal Arcade – Add border