class PQueue:
"""This is a priority queue implementation"""
def __init__(self,A):
self._heap = Heap(A)
def __str__(self):
return str(self._heap.heap[1:])
def peekMax(self):
return self._heap[1]
def extractMax(self):
if self._heap.heapsize < 1:
raise Exception("Heap underflow!")
_max = self._heap[1]
self._heap[1] = self._heap[self._heap.heapsize]
self._heap.heapsize -= 1
self._heap.maxHeapify(1)
return _max
def increaseKey(self,i,key):
if key < self._heap[i]:
raise Exception("New key is smaller than current key")
self._heap[i] = key
while i > 1 and self._heap[self._heap.Parent(i)] < self._heap[i]:
self._heap[i],self._heap[self._heap.Parent(i)] = self._heap[self._heap.Parent(i)],self._heap[i]
i = self._heap.Parent(i)
def insert(self,key):
self._heap.append(float("-inf"))
self.increaseKey(self._heap.heapsize,key);
def heapSort(self,A):
from Heap import Heap
h = Heap(A)
i = len(A)
while i >= 2:
j = h.heap[1]
h.heap [1] = h.heap[i]
h.heap [i] = j
h.heapsize = h.heapsize - 1
h.maxHeapify(1)
i = i-1
return h.heap[1:len(h.heap)]
