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80a885c975
* Updated Pop function Added underflow condition * Update Pop Function Added condition to check underflow of stack * Update stack.py * if not self.stack: raise StackUnderflowError * Add doctests * StackUnderflowError * ..., not .... * Update stack.py Co-authored-by: Christian Clauss <cclauss@me.com>
130 lines
3.2 KiB
Python
130 lines
3.2 KiB
Python
from __future__ import annotations
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class StackOverflowError(BaseException):
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pass
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class StackUnderflowError(BaseException):
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pass
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class Stack:
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"""A stack is an abstract data type that serves as a collection of
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elements with two principal operations: push() and pop(). push() adds an
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element to the top of the stack, and pop() removes an element from the top
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of a stack. The order in which elements come off of a stack are
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Last In, First Out (LIFO).
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https://en.wikipedia.org/wiki/Stack_(abstract_data_type)
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"""
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def __init__(self, limit: int = 10):
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self.stack: list[int] = []
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self.limit = limit
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def __bool__(self) -> bool:
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return bool(self.stack)
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def __str__(self) -> str:
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return str(self.stack)
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def push(self, data):
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"""Push an element to the top of the stack."""
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if len(self.stack) >= self.limit:
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raise StackOverflowError
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self.stack.append(data)
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def pop(self):
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"""
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Pop an element off of the top of the stack.
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>>> Stack().pop()
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Traceback (most recent call last):
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...
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data_structures.stacks.stack.StackUnderflowError
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"""
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if not self.stack:
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raise StackUnderflowError
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return self.stack.pop()
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def peek(self):
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"""
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Peek at the top-most element of the stack.
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>>> Stack().pop()
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Traceback (most recent call last):
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...
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data_structures.stacks.stack.StackUnderflowError
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"""
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if not self.stack:
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raise StackUnderflowError
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return self.stack[-1]
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def is_empty(self) -> bool:
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"""Check if a stack is empty."""
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return not bool(self.stack)
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def is_full(self) -> bool:
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return self.size() == self.limit
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def size(self) -> int:
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"""Return the size of the stack."""
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return len(self.stack)
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def __contains__(self, item) -> bool:
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"""Check if item is in stack"""
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return item in self.stack
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def test_stack() -> None:
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"""
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>>> test_stack()
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"""
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stack = Stack(10)
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assert bool(stack) is False
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assert stack.is_empty() is True
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assert stack.is_full() is False
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assert str(stack) == "[]"
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try:
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_ = stack.pop()
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assert False # This should not happen
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except StackUnderflowError:
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assert True # This should happen
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try:
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_ = stack.peek()
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assert False # This should not happen
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except StackUnderflowError:
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assert True # This should happen
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for i in range(10):
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assert stack.size() == i
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stack.push(i)
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assert bool(stack)
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assert not stack.is_empty()
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assert stack.is_full()
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assert str(stack) == str(list(range(10)))
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assert stack.pop() == 9
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assert stack.peek() == 8
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stack.push(100)
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assert str(stack) == str([0, 1, 2, 3, 4, 5, 6, 7, 8, 100])
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try:
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stack.push(200)
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assert False # This should not happen
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except StackOverflowError:
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assert True # This should happen
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assert not stack.is_empty()
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assert stack.size() == 10
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assert 5 in stack
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assert 55 not in stack
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if __name__ == "__main__":
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test_stack()
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