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Heap.py
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Heap.py
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import math
from Node import *
class MinHeap:
def __init__(self, key):
self.heap = [Node(-1, -1, -1)] #Nodo fittizzio per far partire gli indici da 1
self.heap_size = 0
if(key == 'g' or key == 'h' or key == 'h+g'):
self.key = key #il campo key può valere 'g' = solo costo arco, 'h' = solo eruistica, 'h+g' = costo+euristica
#verrà indicata dall'algoritmo
else:
raise Exception("Funzione di costo non valida")
def parent(self, i):
return math.floor(i/2)
def left(self, i):
return 2*i
def right(self, i):
return 2*i + 1
def is_empty(self):
return self.heap_size == 0
def min_heapify(self, i):
l = self.left(i)
r = self.right(i)
min = i
if l <= self.heap_size and self.heap[l].getKey(self.key) <= self.heap[i].getKey(self.key):
min = l
if r <= self.heap_size and self.heap[r].getKey(self.key) <= self.heap[min].getKey(self.key):
min = r
if min != i:
tmp = self.heap[min]
self.heap[min] = self.heap[i]
self.heap[i] = tmp
self.heap[i].handle = i
self.heap[min].handle = min
self.min_heapify(min)
def minimum(self):
if self.heap_size == 0:
raise Exception("Heap vuoto")
return self.heap[1] #in 0 c'è il nodo sentinella
def insert(self, node):
self.heap.append(node)
self.heap_size = self.heap_size + 1
i = self.heap_size
node.handle = i
#Risalgo
while i > 1 and self.heap[self.parent(i)].getKey(self.key) > self.heap[i].getKey(self.key):
#Switch
tmp = self.heap[self.parent(i)]
self.heap[self.parent(i)] = self.heap[i]
self.heap[i] = tmp
self.heap[i].handle = i
self.heap[self.parent(i)].handle = self.parent(i)
i = self.parent(i)
def decrease_key(self, node, k):
if k > node.getKey(self.key):
raise Exception("Nuova chiave più alta")
node.g = k
i = node.handle
while i > 1 and self.heap[self.parent(i)].getKey(self.key) > self.heap[i].getKey(self.key):
tmp = self.heap[self.parent(i)]
self.heap[self.parent(i)] = self.heap[i]
self.heap[i] = tmp
self.heap[i].handle = i
self.heap[self.parent(i)].handle = self.parent(i)
i = self.parent(i)
def delete(self, node):
i = node.handle
self.heap[i] = self.heap[self.heap_size]
node.handle = -1
self.heap_size = self.heap_size - 1
self.heap.pop()
while i > 1 and self.heap[self.parent(i)].getKey(self.key) > self.heap[i].getKey(self.key):
tmp = self.heap[self.parent(i)]
self.heap[self.parent(i)] = self.heap[i]
self.heap[i] = tmp
self.heap[i].handle = i
self.heap[self.parent(i)].handle = self.parent(i)
i = self.parent(i)
self.min_heapify(i)
def extract_min(self):
if self.heap_size == 0:
raise Exception("Coda vuota")
min = self.heap[1]
min.handle = -1
self.heap[1] = self.heap[self.heap_size]
self.heap[1].handle = 1
self.heap_size = self.heap_size - 1
self.heap.pop()
self.min_heapify(1)
return min
def print_heap(self):
print("Heap: ")
print("heap_size = ", self.heap_size)
print("heap len = ", len(self.heap) - 1 )
for i in range(1,self.heap_size+1):
print("",self.heap[i].getID(),": ",self.heap[i].getKey(self.key),"")