#19MediumThread Synchronization· Semaphores and Turn Taking

Print FooBar Alternately

A `FooBar` object is created with an integer `n` and shared by two threads. One thread calls `foo()`, which prints `foo` `n` times in a loop; the other calls `bar()`, which prints `bar` `n` times. Add synchronisation so that the combined output is exactly `foobar` repeated `n` times: every `foo` is immediately followed by a `bar`, and the first word is always `foo`, regardless of which thread starts first or how the scheduler interleaves them. Do not use sleeps or busy-waiting. **Test format.** The input is `n`; the output is everything printed, concatenated.

Input format

n: number of foo/bar pairs to print

Output format

String: "foobar" repeated n times

Examples

Input: n = 1

Output: foobar

One foo followed by one bar.

Input: n = 2

Output: foobarfoobar

The threads alternate: foo, bar, foo, bar.

Constraints

1 <= n <= 1000

Study first

Operating Systems & Concurrency

#concurrency
#threads
#semaphores
#synchronization