Fixed heap_sort_c++

[yamanalrfai]

there some logical bugs in C++ code for the heap_sort

in a C++ version of heap_sort there are 3 wrongs

1. the function minheapify (line: 49)
   if (l >= limit || r >= limit)
return;
   using || is not right because if the r >= limit then it never check the left node.
   so we must cheek like this:

void minheapify(int i, int limit) {
  int l = left(i);
  int r = right(i);
  int smallest = i;
  if (l < limit && harr[l] < harr[i])
    smallest = l;
  if (r < limit && harr[r] < harr[smallest])
    smallest = r;
  if (i != smallest) {
    swap( & harr[i], & harr[smallest]);
    minheapify(smallest, limit);
  }
}

2. the function sort() (line: 64)
   for (i = 1; i < heap_size - 1; i++) {
   it must be
   for (i = 1; i < heap_size; i++) {

3. need to add buildHeap before start the sort so it become

void buildHeap() {
  for (int i = (heap_size / 2) - 1; i >= 0; i--) {
    minheapify(i, heap_size);
  }
}

void sort() {
  buildHeap(); 
  int i;
  for (i = 1; i < heap_size; i++) {
    swap( & harr[0], & harr[heap_size - i]);
    minheapify(0, heap_size - i);
  }
}

and for Memory leek use Destructor

~heap() {
  delete[] harr;
}

I will not add this Because your class manages a raw memory pointer (harr), if you ever tried to copy this heap like this:
heap h2 = h;
...both heaps would point to the exact same array in memory. Modifying one would break the other, and when they are destroyed, the program would try to delete[] the same memory twice, causing a crash.

I will open a PR to add this thing
here it if still you need it after 6 years : https://github.com/matthewsamuel95/ACM-ICPC-Algorithms/pull/1060/changes