a collection of white boarding solutions
####combine-nth-elements: should take in a two dimensional array and an empty array. Returns a single array containing all the elements of the inner array while maintaining each nth element's order with respect to their original array
combineNthElement([[3,5,8], [4,2], [4,5,9,23], [7,4,4]],[]);
//[3,4,4,7,5,2,5,4,8,9,4,23]
####firstUnique: input: string of letters consisting of a-z, no spaces output: first letter occurs only once or if all letters have a duplicate returns ''
firstUnique('aaabcccddeff');
//b