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Speeding things up There are several things you could do to speed things up: Instead of looping from 100..999, go from 999..100 instead. That way, if you find a palindrome, you can break from the j …

Faster sorting If the only purpose of the distance computation is for comparison, then you can speed it up by removing the call to sqrt(). You'll end up comparing the squares of the distances, which …

Repeating work already done The biggest problem with your solution is that for each test case, you start over from scratch. This causes you to do up to 10x the work that you need to do. What you sho …

Bug I ran your program, replacing 100 with 6. This should have found the subset {2,4} as a solution but it didn't. Your program searches for contiguous subsets which sum to the given value. I don't …

Bug This line in your quicksort isn't right: int pivot = toSort[(rand() % endPtr - beginPtr + 1) + beginPtr]; It should be: int pivot = toSort[rand() % (endPtr - beginPtr) + beginPtr]; Notice that …

Memory ordering problem This line: if (first == m_last.load(std::memory_order_relaxed)) return false; should be: if (first == m_last.load(std::memory_order_acquire)) …

Stop printing so much I ran your program and found that it spent most of its time printing every single combination (even though none of them were solutions). After I removed the line that prints the …

ABA problem It looks like your allocator is susceptible to the ABA problem. The allocate() function's compare and exchange is unsafe because the "next" value you are exchanging could be invalid by t …

ABA problem I was able to break your queue (but it wasn't easy). I inserted some code to freeze one thread here in consume(): do{ // The divider's next pointer points to the next node wit …

Reducing number of writes Right now, you swap neighboring elements until the newest element reaches its proper place. This takes 2n array writes to move an element n spots. Instead of swapping, you …

More efficient way Your current algorithm runs in \$O(N^2)\$ time. At the time I started thinking about this, I did not read Jerry Coffin's link that demonstrated an \$O(N)\$ solution, so I came up …

Problem 1 Consider that register_idle() is equivalent to this slightly rewritten version: // this function is called by each thread when it is about to sleep void register_idle(size_t thread_id) { …

Too complex With the problem constrained to: The elements of the sequence are integers in range [0, 99] The length of the sequence is in range [0, 50] the program should be very simple. Instead, yo …

Pop() has problem Consider what happens if your queue is in the following state with two jobs: m_top = 0 m_bottom = 2 The owner thread calls pop(), and loads in to local variables: top = 0 bott …

Likely or unlikely? I didn't run your code, but something didn't make sense to me when I was reading it. You use an unlikely macro in several of your loops. But it seems to me that these should be l …