Array of Linked Lists C++

That returns a bunch of unallocated pointers. Your top level array is fine, but its elements are still uninitialized pointers, so when you do this: You invoke undefined behavior. You’re dereferencing an uninitialized pointer. You allocated the array properly, now you need to allocate each pointer, i.e., As an aside, I realize that you’re learning, … Read more

Queue vs Dequeue in java

Deque is short for “double ended queue”. With an ordinary queue, you add things to one end and take them from the other. With a double ended queue, you can add things to either end, and take them from either end. That makes it a bit more versatile; for example, you could use it as … Read more

Difference between O(n) and O(log(n)) – which is better and what exactly is O(log(n))?

It means that the thing in question (usually running time) scales in a manner that is consistent with the logarithm of its input size. Big-O notation doesn’t mean an exact equation, but rather a bound. For instance, the output of the following functions is all O(n): Because as you increase x, their outputs all increase linearly – if there’s … Read more