[碩.Love Python] BinomialHeap(B堆 & 二項堆)

2019-11-08 19:43:35

字體：大中小

來源：轉載

供稿：網友

class Node(object): def __init__(self, data): self.data = data self.child = None self.left = None self.right = None self.degree = 0 def __str__(self): return str(self.data) __rePR__ = __str__class BinomialHeap(object): MAX_DEGREE = 20 def __init__(self): self.root = None def combine(self, heap): self._dlistCombine(self.root, heap.root) if heap.root.data < self.root.data: self.root = heap.root def insert(self, data): node = Node(data) if self.root is None: self.root = node self._initSiblingList(node) else: self._addSibling(self.root, node) if data < self.root.data: self.root = node def pop(self): if self.root is None: raise ValueError('pop from empty heap.') res = self.root.data children = self.root.child siblings = self._dlistDelete(self.root) self.root = self._rebuild(children, siblings) return res def _rebuild(self, children, siblings): if children is None and siblings is None: return None treeArr = [None] * BinomialHeap.MAX_DEGREE self._combineTrees(treeArr, children) self._combineTrees(treeArr, siblings) head = None treeIterator = iter(treeArr) for node in treeIterator: if node: break root = head = prev = node for node in treeIterator: if node: prev.right = node node.left = prev prev = node if node.data < root.data: root = node head.left = prev prev.right = head return root def _combineTrees(self, treeArr, head): if head is None: return node = head while True: tmp = node node = node.right for i in xrange(tmp.degree, len(treeArr)): if treeArr[i] is None: break tmp = self._joinTree(tmp, treeArr[i]) treeArr[i] = None else: raise Exception('max degree') treeArr[i] = tmp if node is head: break def _joinTree(self, tree1, tree2): if tree2.data < tree1.data: tree1, tree2 = tree2, tree1 self._addChild(tree1, tree2) return tree1 def _dlistInit(self, head): head.left = head.right = head def _dlistCombine(self, head1, head2): r1 = head1.right l2 = head2.left head1.right = head2 head2.left = head1 r1.left = l2 l2.right = r1 def _dlistInsert(self, head, node): node.left = head node.right = head.right node.right.left = node head.right = node def _dlistDelete(self, node): if node.left is node: newHead = None else: node.left.right = node.right node.right.left = node.left newHead = node.right return newHead _initSiblingList = _dlistInit _addSibling = _dlistInsert def _addChild(self, parent, child): if parent.child is None: parent.child = child self._initSiblingList(child) else: self._addSibling(parent.child, child) parent.degree += 1if __name__ == '__main__': from random import sample data = range(1, 100000) data1 = sample(data, 1000) data2 = sample(data, 20000) heap1 = BinomialHeap() map(heap1.insert, data1) for _ in xrange(100): print heap1.pop(), print heap2 = BinomialHeap() map(heap2.insert, data2) heap1.combine(heap2) print '-' * 80 for _ in xrange(200):

print heap1.pop(),

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