I was asked this question in an interview. I was pretty clueless. So I decided to learn some multithreading and hopefully find an answer to this question.
I need to use 3 threads to print the output: 01020304050607.....
- Thread1: prints 0
- Thread2: prints odd numbers
- Thread3: prints even numbers
#include <iostream>
#include <thread>
#include <mutex>
#include <condition_variable>
std::mutex m;
std::condition_variable cv1, cv2, cv3;
int count = 0;
void printzero(int end)
{
while (count <= end)
{
std::unique_lock<std::mutex> lock(m);
cv1.wait(lock);
std::cout << 0 << " ";
++count;
if (count % 2 == 1)
{
lock.unlock();
cv2.notify_one();
}
else
{
lock.unlock();
cv3.notify_one();
}
}
}
void printodd(int end)
{
while (count <= end)
{
std::unique_lock<std::mutex> lock(m);
cv2.wait(lock);
if (count % 2 == 1)
{
std::cout << count << " ";
++count;
lock.unlock();
cv1.notify_one();
}
}
}
void printeven(int end)
{
while (count <= end)
{
std::unique_lock<std::mutex> lock(m);
cv3.wait(lock);
if (count % 2 == 0)
{
std::cout << count << " ";
++count;
lock.unlock();
cv1.notify_one();
}
}
}
int main()
{
int end = 10;
std::thread t3(printzero, end);
std::thread t1(printodd, end);
std::thread t2(printeven, end);
cv1.notify_one();
t1.join();
t2.join();
t3.join();
return 0;
}
My solution seems to be in a deadlock situation. I'm not even sure if the logic is correct. Please help
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