Lecture 10_ Heaps.pptx - Lecture 10 Heaps Heaps type of...

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Lecture 10: Heaps
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Heaps type of binary tree complete all leaves are only at the bottom layer heap order parent has higher priority than its children (priority varies) implemented using arrays optimal runtime for sorting
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Heap Implementation reheapUp() and reheapDown() methods swap parent with children or vice versa depending on priority insert() add it to the end of the array, then reheapUp() poll() swap with last element in heap, then reheapDown() O(log n) runtime, iterate for the number of levels
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Indexes of a Heap root at index 0 left child from Node at index n = 2 * n + 1 right child from Node at index = 2 * n + 2 parent from Node at index n = (n - 1) / 2
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Priority Queues in Java PriorityQueue<E>() - default Priority Queue, smallest elements at top (lowest priority) PriorityQueue<E>(int size, Comparator<E> c) - custom comparator boolean add(E)/offer(E) - insert element into Priority Queue void clear() - clear Priority Queue E peek() - get top element of Priority Queue, don’t remove it E poll() - remove top element of Priority Queue
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Comparator<E> PriorityQueue<Integer> pQueue = new PriorityQueue<Integer>(1000, new Comparator< Integer >() {
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