Step 1: Understand what space complexity means. Space complexity measures how much extra memory an algorithm uses as the input size grows.
Step 2: Know that Heap Sort is an in-place sorting algorithm. This means it sorts the elements within the same array without needing extra space for another array.
Step 3: Realize that since Heap Sort only uses a fixed amount of extra space (for variables and pointers), it does not depend on the size of the input array.
Step 4: Conclude that the space complexity of Heap Sort is O(1), which means it uses constant space.
