public IEnumerable<int> KSE_MinHeap(int[] A, int K){
var heap = new int[K];
for(int i=0; i<heap.Length; i++)
heap[i] = A[i];
var pq = new MinPQ(heap);
for(int i=K; i<A.Length; i++)
pq.InsertAtTop(A[i]);
foreach(var i in pq.PQ())
yield return i;
}