Was referred by a friend. Skipped the phone screen interview because I was interviewing with Facebook at the same time. Was flown to Mountain View to go through the five interviews in one day process. Was interviewing for the Android and Display Ads teams. An Android team member asked me this question, which I wasn't able to finish in time.

main() { A() C() }

A() { B() }

B() {} C() {}

input: t1 main enter t2 A enter t3 B enter t4 B exit t5 A exit t6 C enter t7 C exit t8 main exit

output: main (t8-t1) A (t5-t2) B (t4-t3) C (t7-t6)

Write a function that, given the input, will create the output.

Write a function that, given a sequence and a number b between [-10,10], will return a new sequence. Sequences are generated by this: http://en.wikipedia.org/wiki/Look-and-say_sequence.

A number b, if equal to 0, the function will return the input sequence.

Valid sequences: 1 11 21 1211 111221 ...

Example: input: 1211, +1 output: 111221

Example: input: 111221, -1 output: 1211