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LeetCode solutions

1187. Print FooBar Alternately

My accepted Python solution to LeetCode problem 1187, Print FooBar Alternately, running in 65ms.

  • Difficulty: Medium
  • Python
  • Runtime 65ms
  • Memory 17.7MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 65ms, memory 17.7MB, accepted 2026-01-02.

python
from threading import Lock

class FooBar:
    def __init__(self, n):
        self.n = n
        self.foo_lock = Lock()
        self.bar_lock = Lock()
        self.bar_lock.acquire()

    def foo(self, printFoo: 'Callable[[], None]') -> None:
        for i in range(self.n):
            self.foo_lock.acquire()
            printFoo()
            self.bar_lock.release()

    def bar(self, printBar: 'Callable[[], None]') -> None:
        for i in range(self.n):
            self.bar_lock.acquire()
            printBar()
            self.foo_lock.release()

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