tvl-depot/scratch/facebook/largest-stack.py

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from stack import Stack, from_list
from heapq import heapify, heappush, heappop
from random import shuffle
class MaxStack(Stack):
def __init__(self):
self.max = Stack()
super().__init__()
def __repr__(self):
return super().__repr__()
def push(self, x):
super().push(x)
max = self.get_max()
if not max:
self.max.push(x)
else:
self.max.push(max if x < max else x)
def pop(self):
self.max.pop()
return super().pop()
def get_max(self):
return self.max.peek()
xs = list(range(1, 11))
shuffle(xs)
stack = MaxStack()
for x in xs:
stack.push(x)
print(stack)
result = stack.get_max()
print(result)
assert result == 10
popped = stack.pop()
print("Popped: {}".format(popped))
print(stack)
while popped != 10:
assert stack.get_max() == 10
popped = stack.pop()
print("Popped: {}".format(popped))
print(stack)
assert stack.get_max() != 10
print("Success!")