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Fix the issue in FIFO retrieval in priorityQueueHeap.py #15

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Fix the issue in FIFO retrieval in priorityQueueHeap.py #15

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24 changes: 11 additions & 13 deletions Chapter07/priorityQueueHeap.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,26 +5,28 @@ def __init__(self):

def arrange(self, k):
while k // 2 > 0:
if self.heap[k][0] < self.heap[k//2][0]:
self.heap[k], self.heap[k//2] = self.heap[k//2], self.heap[k]
if self.heap[k][0] >= self.heap[k // 2][0]:
break
self.heap[k], self.heap[k // 2] = self.heap[k // 2], self.heap[k]
k //= 2

def insert(self,priority, item):
def insert(self, priority, item):
self.heap.append((priority, item))
self.size += 1
self.arrange(self.size)

def sink(self, k):
while k * 2 <= self.size:
mc = self.minchild(k)
if self.heap[k][0] > self.heap[mc][0]:
self.heap[k], self.heap[mc] = self.heap[mc], self.heap[k]
if self.heap[k][0] < self.heap[mc][0]:
break
self.heap[k], self.heap[mc] = self.heap[mc], self.heap[k]
k = mc

def minchild(self, k):
if k * 2 + 1 > self.size:
return k * 2
elif self.heap[k*2][0] < self.heap[k*2+1][0]:
elif self.heap[k * 2][0] <= self.heap[k * 2 + 1][0]:
return k * 2
else:
return k * 2 + 1
Expand All @@ -38,10 +40,9 @@ def delete_at_root(self):
return item



h = PriorityQueueHeap()
h.insert(2, "Bat")
h.insert(13,"Cat")
h = PriorityQueueHeap()
h.insert(2, "Bat")
h.insert(13, "Cat")
h.insert(18, "Rat")
h.insert(26, "Ant")
h.insert(3, "Lion")
Expand All @@ -54,6 +55,3 @@ def delete_at_root(self):
n = h.delete_at_root()
print(n)
print(h.heap)