CSHARP

MinHeap c#

public class MinHeap
        {
            private readonly int[] _elements;
            private int _size;

            public MinHeap(int size)
            {
                _elements = new int[size];
            }

            private int GetLeftChildIndex(int elementIndex) => 2 * elementIndex + 1;
            private int GetRightChildIndex(int elementIndex) => 2 * elementIndex + 2;
            private int GetParentIndex(int elementIndex) => (elementIndex - 1) / 2;

            private bool HasLeftChild(int elementIndex) => GetLeftChildIndex(elementIndex) < _size;
            private bool HasRightChild(int elementIndex) => GetRightChildIndex(elementIndex) < _size;
            private bool IsRoot(int elementIndex) => elementIndex == 0;

            private int GetLeftChild(int elementIndex) => _elements[GetLeftChildIndex(elementIndex)];
            private int GetRightChild(int elementIndex) => _elements[GetRightChildIndex(elementIndex)];
            private int GetParent(int elementIndex) => _elements[GetParentIndex(elementIndex)];

            private void Swap(int firstIndex, int secondIndex)
            {
                var temp = _elements[firstIndex];
                _elements[firstIndex] = _elements[secondIndex];
                _elements[secondIndex] = temp;
            }

            public bool IsEmpty()
            {
                return _size == 0;
            }

            public int Peek()
            {
                if (_size == 0)
                    throw new IndexOutOfRangeException();

                return _elements[0];
            }

            public int Pop()
            {
                if (_size == 0)
                    throw new IndexOutOfRangeException();

                var result = _elements[0];
                _elements[0] = _elements[_size - 1];
                _size--;

                ReCalculateDown();

                return result;
            }

            public void Add(int element)
            {
                if (_size == _elements.Length)
                    throw new IndexOutOfRangeException();

                _elements[_size] = element;
                _size++;

                ReCalculateUp();
            }

            private void ReCalculateDown()
            {
                int index = 0;
                while (HasLeftChild(index))
                {
                    var smallerIndex = GetLeftChildIndex(index);
                    if (HasRightChild(index) && GetRightChild(index) < GetLeftChild(index))
                    {
                        smallerIndex = GetRightChildIndex(index);
                    }

                    if (_elements[smallerIndex] >= _elements[index])
                    {
                        break;
                    }

                    Swap(smallerIndex, index);
                    index = smallerIndex;
                }
            }

            private void ReCalculateUp()
            {
                var index = _size - 1;
                while (!IsRoot(index) && _elements[index] < GetParent(index))
                {
                    var parentIndex = GetParentIndex(index);
                    Swap(parentIndex, index);
                    index = parentIndex;
                }
            }
        }