|
| 1 | +#!/usr/bin/python3 |
| 2 | +""" |
| 3 | +Suppose you are given the following code: |
| 4 | +
|
| 5 | +class FooBar { |
| 6 | + public void foo() { |
| 7 | + for (int i = 0; i < n; i++) { |
| 8 | + print("foo"); |
| 9 | + } |
| 10 | + } |
| 11 | +
|
| 12 | + public void bar() { |
| 13 | + for (int i = 0; i < n; i++) { |
| 14 | + print("bar"); |
| 15 | + } |
| 16 | + } |
| 17 | +} |
| 18 | +The same instance of FooBar will be passed to two different threads. Thread A |
| 19 | +will call foo() while thread B will call bar(). Modify the given program to |
| 20 | +output "foobar" n times. |
| 21 | +
|
| 22 | +
|
| 23 | +
|
| 24 | +Example 1: |
| 25 | +
|
| 26 | +Input: n = 1 |
| 27 | +Output: "foobar" |
| 28 | +Explanation: There are two threads being fired asynchronously. One of them calls |
| 29 | +foo(), while the other calls bar(). "foobar" is being output 1 time. |
| 30 | +Example 2: |
| 31 | +
|
| 32 | +Input: n = 2 |
| 33 | +Output: "foobarfoobar" |
| 34 | +Explanation: "foobar" is being output 2 times. |
| 35 | +""" |
| 36 | +fromthreadingimportLock |
| 37 | +fromtypingimportCallable |
| 38 | + |
| 39 | + |
| 40 | +classFooBar: |
| 41 | +def__init__(self,n): |
| 42 | +self.n=n |
| 43 | +self.locks= [Lock(),Lock()] |
| 44 | +self.locks[1].acquire() |
| 45 | + |
| 46 | + |
| 47 | +deffoo(self,printFoo:Callable[[],None])->None: |
| 48 | +foriinrange(self.n): |
| 49 | +self.locks[0].acquire() |
| 50 | +# printFoo() outputs "foo". Do not change or remove this line. |
| 51 | +printFoo() |
| 52 | +self.locks[1].release() |
| 53 | + |
| 54 | + |
| 55 | +defbar(self,printBar:Callable[[],None])->None: |
| 56 | +foriinrange(self.n): |
| 57 | +self.locks[1].acquire() |
| 58 | +# printBar() outputs "bar". Do not change or remove this line. |
| 59 | +printBar() |
| 60 | +self.locks[0].release() |