U++ learning note pile

Heapify Any existing array can be turned into a heap by calling this function . This is overloaded to accept predicates or not , The non predicate version will use the element type operator< To determine the sort ：

TArray<int32> HeapArr;
for (int32 Val = 10; Val != 0; --Val)
{
    HeapArr.Add(Val);
}
// HeapArr == [10,9,8,7,6,5,4,3,2,1]
HeapArr.Heapify();
// HeapArr == [1,2,4,3,6,5,8,10,7,9]

Can pass HeapPush Function to add a new element to the heap , Reorder other nodes to maintain the heap  

HeapArr.HeapPush(4);
// HeapArr == [1,2,4,3,4,5,8,10,7,9,6]

The and functions are used to delete the top node from the heap HeapPop.HeapPopDiscard The difference between the two is that the former uses a reference to the element type to return a copy of the top element , The latter simply removes the top node without returning it in any way . Both functions make the same changes to the array , And maintain the heap again by reordering other elements appropriately ：

int32 TopNode;
HeapArr.HeapPop(TopNode);
// TopNode == 1
// HeapArr == [2,3,4,6,4,5,8,10,7,9]

HeapRemoveAt An element will be deleted from the array at the given index , Then reorder the elements to maintain the heap ：

HeapArr.HeapRemoveAt(1);
// HeapArr == [2,4,4,6,9,5,8,10,7]

Each of these functions , Include Heapify, You can use optional binary predicates to determine the order of node elements in the heap . By default , Heap operations use element types operator< To determine the order . When using custom predicates , It is important to use the same predicate for all heap operations .

Last , have access to To check the top node of the heap HeapTop, Without changing the array ：

int32 Top = HeapArr.HeapTop();
// Top == 2