Is Print Zero Even Odd easy or hard?

Print Zero Even Odd is typically rated Medium because the logic itself is simple but implementing correct thread synchronization can be tricky. Developers must prevent race conditions and ensure threads execute in the exact required order.

How to solve Print Zero Even Odd in O(n)?

Use synchronization primitives to enforce execution order between threads. With semaphores, the zero thread prints 0 and releases either the odd or even semaphore. The corresponding thread prints its number and signals the zero thread again. Each step happens once per number, resulting in O(n) time.

Print Zero Even Odd Python or Java solution

Python implementations often use a mutex with condition variables from the threading module. Java solutions commonly use Semaphore from java.util.concurrent. Both approaches maintain O(n) time complexity while ensuring threads print in the correct sequence.

What is the best approach for Print Zero Even Odd?

The semaphore-based approach is generally the cleanest solution. It uses three semaphores to control which thread prints next, ensuring the sequence 0, number, 0, number continues correctly. This approach runs in O(n) time with O(1) extra space and avoids complex condition checks.

What data structure is used in Print Zero Even Odd?

The problem does not rely on traditional data structures like arrays or hash maps. Instead, it uses concurrency primitives such as mutex locks, condition variables, or semaphores to coordinate thread execution and maintain the correct printing order.

What is the time complexity of Print Zero Even Odd?

The time complexity is O(n) because each number from 1 to n is printed once and each print involves a constant number of synchronization operations. Space complexity is O(1) since only a few shared variables or semaphores are used.

Is Print Zero Even Odd asked at Google, Amazon, or Meta?

Concurrency coordination problems like Print Zero Even Odd appear in interviews at companies that test multithreading knowledge, including Google, Amazon, and Meta. Interviewers use them to evaluate understanding of synchronization primitives such as mutexes, condition variables, and semaphores.

Description Solution Video 14:57

1116. Print Zero Even Odd

Medium62.0% acceptance2 companies

You have a function printNumber that can be called with an integer parameter and prints it to the console.

For example, calling printNumber(7) prints 7 to the console.

You are given an instance of the class ZeroEvenOdd that has three functions: zero, even, and odd. The same instance of ZeroEvenOdd will be passed to three different threads:

Thread A: calls zero() that should only output 0's.
Thread B: calls even() that should only output even numbers.
Thread C: calls odd() that should only output odd numbers.

Modify the given class to output the series "010203040506..." where the length of the series must be 2n.

Implement the ZeroEvenOdd class:

ZeroEvenOdd(int n) Initializes the object with the number n that represents the numbers that should be printed.
void zero(printNumber) Calls printNumber to output one zero.
void even(printNumber) Calls printNumber to output one even number.
void odd(printNumber) Calls printNumber to output one odd number.

Example 1:

Input: n = 2
Output: "0102"
Explanation: There are three threads being fired asynchronously.
One of them calls zero(), the other calls even(), and the last one calls odd().
"0102" is the correct output.

Example 2: