Heap, Build a Max-heap and Convert Binary tree into a Heap using Dart programming Language

heap.dart

int left(int i) {
  return 2 * i;
}

int right(int i) {
  return 2 * i - 1;
}

int parant(int i) {
  return i;
}

bool isMaxheap(heap) {
  int n = heap.length - 1;

  for (int i = n; i > 0; i--) {
    int p = parant(i);
    if (heap[p] < heap[i]) {
      return false;
    } else
      true;
  }
}

List maxHeapify(List heap, int heap_size, var i) {
  int l = left(i);
  int r = right(i);
  int largest;
  if (l <= heap_size && heap[l] > heap[i]) {
    largest = l;
  } else
    largest = i;
  if (r <= heap_size && heap[r] > heap[largest]) {
    largest = r;
  }
  if (largest != i) {
    // swap(heap[i], heap[largest]);
    var temp = heap[i];
    heap[i] = heap[largest];
    heap[largest] = temp;
    maxHeapify(heap, heap_size, largest);
  }
}

List buildMaxHeap(List heap) {
  int heap_size = heap.length - 1;
  for (var i = heap_size / ~2; i < 0; i--) {
    maxHeapify(heap, heap_size, i);
  }
}

main(List<String> args) {
  List H = [null, 19, 7, 12, 3, 5, 17, 10, 1, 2];
  print(H);
  maxHeapify(H, 9, 3);
  print(H);
  print("========================================");
  List h = [null, 1, 2, 3];
  print(h);
  maxHeapify(h, 3, 1);
  print(h);
}