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min_stack.py
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min_stack.py
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# Copyright [2018] [Haibo Yan]
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
class MinStack:
def __init__(self):
self._stack = []
def push(self, e):
if len(self._stack) == 0:
self._stack.append((e, e))
else:
m = min(self._stack[-1][1], e)
self._stack.append((e, m))
def pop(self):
l = self._stack.pop(-1)
return l[0]
def top(self):
return self._stack[-1][0]
def empty(self):
return len(self._stack) == 0
def min(self):
return self._stack[-1][1]