How do we use a heap?

You'll rarely write sift up and sift down yourself. Python, Java and C++ each ship a heap — and JavaScript doesn't, so this course writes one small class once and reuses it everywhere. Here's each language's heap, how to make it order things your way, and the traps that cost people marks.

The built-in heap in each language

The same small job in all four: put some numbers in a min-heap, then take them all out. They come out smallest first.