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Merged
merged 4 commits into from
Sep 13, 2020
Merged

Updated Stack #2414

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8a8dca5
* Added type hints
realDuYuanChao Sep 10, 2020
f7d98be
updating DIRECTORY.md
Sep 10, 2020
d686f88
Update stack.py
cclauss Sep 13, 2020
c8b2679
Test error conditions for pop, peek, and
cclauss Sep 13, 2020
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20 changes: 19 additions & 1 deletion DIRECTORY.md
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,9 @@
* [Sudoku](https://github.com/TheAlgorithms/Python/blob/master/backtracking/sudoku.py)
* [Sum Of Subsets](https://github.com/TheAlgorithms/Python/blob/master/backtracking/sum_of_subsets.py)

## Bit Manipulation
* [Binary Or Operator](https://github.com/TheAlgorithms/Python/blob/master/bit_manipulation/binary_or_operator.py)

## Blockchain
* [Chinese Remainder Theorem](https://github.com/TheAlgorithms/Python/blob/master/blockchain/chinese_remainder_theorem.py)
* [Diophantine Equation](https://github.com/TheAlgorithms/Python/blob/master/blockchain/diophantine_equation.py)
Expand All @@ -50,6 +53,7 @@
* [Deterministic Miller Rabin](https://github.com/TheAlgorithms/Python/blob/master/ciphers/deterministic_miller_rabin.py)
* [Diffie](https://github.com/TheAlgorithms/Python/blob/master/ciphers/diffie.py)
* [Elgamal Key Generator](https://github.com/TheAlgorithms/Python/blob/master/ciphers/elgamal_key_generator.py)
* [Enigma Machine2](https://github.com/TheAlgorithms/Python/blob/master/ciphers/enigma_machine2.py)
* [Hill Cipher](https://github.com/TheAlgorithms/Python/blob/master/ciphers/hill_cipher.py)
* [Mixed Keyword Cypher](https://github.com/TheAlgorithms/Python/blob/master/ciphers/mixed_keyword_cypher.py)
* [Morse Code Implementation](https://github.com/TheAlgorithms/Python/blob/master/ciphers/morse_code_implementation.py)
Expand Down Expand Up @@ -105,6 +109,7 @@
* [Segment Tree Other](https://github.com/TheAlgorithms/Python/blob/master/data_structures/binary_tree/segment_tree_other.py)
* [Treap](https://github.com/TheAlgorithms/Python/blob/master/data_structures/binary_tree/treap.py)
* Disjoint Set
* [Alternate Disjoint Set](https://github.com/TheAlgorithms/Python/blob/master/data_structures/disjoint_set/alternate_disjoint_set.py)
* [Disjoint Set](https://github.com/TheAlgorithms/Python/blob/master/data_structures/disjoint_set/disjoint_set.py)
* Hashing
* [Double Hash](https://github.com/TheAlgorithms/Python/blob/master/data_structures/hashing/double_hash.py)
Expand Down Expand Up @@ -419,6 +424,7 @@
* [Sum Of Geometric Progression](https://github.com/TheAlgorithms/Python/blob/master/maths/sum_of_geometric_progression.py)
* [Test Prime Check](https://github.com/TheAlgorithms/Python/blob/master/maths/test_prime_check.py)
* [Trapezoidal Rule](https://github.com/TheAlgorithms/Python/blob/master/maths/trapezoidal_rule.py)
* [Ugly Numbers](https://github.com/TheAlgorithms/Python/blob/master/maths/ugly_numbers.py)
* [Volume](https://github.com/TheAlgorithms/Python/blob/master/maths/volume.py)
* [Zellers Congruence](https://github.com/TheAlgorithms/Python/blob/master/maths/zellers_congruence.py)

Expand Down Expand Up @@ -474,6 +480,7 @@
* [Sdes](https://github.com/TheAlgorithms/Python/blob/master/other/sdes.py)
* [Sierpinski Triangle](https://github.com/TheAlgorithms/Python/blob/master/other/sierpinski_triangle.py)
* [Tower Of Hanoi](https://github.com/TheAlgorithms/Python/blob/master/other/tower_of_hanoi.py)
* [Triplet Sum](https://github.com/TheAlgorithms/Python/blob/master/other/triplet_sum.py)
* [Two Sum](https://github.com/TheAlgorithms/Python/blob/master/other/two_sum.py)
* [Word Patterns](https://github.com/TheAlgorithms/Python/blob/master/other/word_patterns.py)

Expand Down Expand Up @@ -600,6 +607,12 @@
* [Solution42](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_42/solution42.py)
* Problem 43
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_43/sol1.py)
* Problem 44
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_44/sol1.py)
* Problem 45
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_45/sol1.py)
* Problem 46
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_46/sol1.py)
* Problem 47
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_47/sol1.py)
* Problem 48
Expand All @@ -608,10 +621,14 @@
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_52/sol1.py)
* Problem 53
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_53/sol1.py)
* Problem 55
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_55/sol1.py)
* Problem 551
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_551/sol1.py)
* Problem 56
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_56/sol1.py)
* Problem 63
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_63/sol1.py)
* Problem 67
* [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_67/sol1.py)
* Problem 76
Expand Down Expand Up @@ -673,7 +690,6 @@
* [Recursive Insertion Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/recursive_insertion_sort.py)
* [Selection Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/selection_sort.py)
* [Shell Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/shell_sort.py)
* [Sleep Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/sleep_sort.py)
* [Stooge Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/stooge_sort.py)
* [Strand Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/strand_sort.py)
* [Tim Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/tim_sort.py)
Expand All @@ -685,6 +701,7 @@
## Strings
* [Aho-Corasick](https://github.com/TheAlgorithms/Python/blob/master/strings/aho-corasick.py)
* [Boyer Moore Search](https://github.com/TheAlgorithms/Python/blob/master/strings/boyer_moore_search.py)
* [Capitalize](https://github.com/TheAlgorithms/Python/blob/master/strings/capitalize.py)
* [Check Anagrams](https://github.com/TheAlgorithms/Python/blob/master/strings/check_anagrams.py)
* [Check Pangram](https://github.com/TheAlgorithms/Python/blob/master/strings/check_pangram.py)
* [Is Palindrome](https://github.com/TheAlgorithms/Python/blob/master/strings/is_palindrome.py)
Expand Down Expand Up @@ -715,6 +732,7 @@
* [Emails From Url](https://github.com/TheAlgorithms/Python/blob/master/web_programming/emails_from_url.py)
* [Fetch Bbc News](https://github.com/TheAlgorithms/Python/blob/master/web_programming/fetch_bbc_news.py)
* [Fetch Github Info](https://github.com/TheAlgorithms/Python/blob/master/web_programming/fetch_github_info.py)
* [Fetch Jobs](https://github.com/TheAlgorithms/Python/blob/master/web_programming/fetch_jobs.py)
* [Get Imdb Top 250 Movies Csv](https://github.com/TheAlgorithms/Python/blob/master/web_programming/get_imdb_top_250_movies_csv.py)
* [Get Imdbtop](https://github.com/TheAlgorithms/Python/blob/master/web_programming/get_imdbtop.py)
* [Slack Message](https://github.com/TheAlgorithms/Python/blob/master/web_programming/slack_message.py)
Expand Down
51 changes: 27 additions & 24 deletions data_structures/stacks/stack.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,3 @@
__author__ = "Omkar Pathak"


class Stack:
"""A stack is an abstract data type that serves as a collection of
elements with two principal operations: push() and pop(). push() adds an
Expand All @@ -11,14 +8,14 @@ class Stack:
https://en.wikipedia.org/wiki/Stack_(abstract_data_type)
"""

def __init__(self, limit=10):
def __init__(self, limit: int = 10):
self.stack = []
self.limit = limit

def __bool__(self):
def __bool__(self) -> bool:
return bool(self.stack)

def __str__(self):
def __str__(self) -> str:
return str(self.stack)

def push(self, data):
Expand All @@ -29,21 +26,24 @@ def push(self, data):

def pop(self):
""" Pop an element off of the top of the stack."""
if self.stack:
return self.stack.pop()
else:
if self.is_empty():
raise IndexError("pop from an empty stack")
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Does it do exactly the same thing if you remove lines 29 and 30?

return self.stack.pop()

def peek(self):
""" Peek at the top-most element of the stack."""
if self.stack:
return self.stack[-1]
if self.is_empty():
raise IndexError("peek from an empty stack")
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Does it do a similar thing if you remove lines 35 and 36?

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Line3 35 and 36 execute when stack is empty. assert() statements will still be successful if i remove them .

return self.stack[-1]

def is_empty(self):
def is_empty(self) -> bool:
""" Check if a stack is empty."""
return not bool(self.stack)

def size(self):
def is_full(self) -> bool:
return self.size() == self.limit

def size(self) -> int:
""" Return the size of the stack."""
return len(self.stack)

Expand All @@ -57,19 +57,22 @@ class StackOverflowError(BaseException):


if __name__ == "__main__":
stack = Stack()
stack = Stack(10)
for i in range(10):
stack.push(i)

print("Stack demonstration:\n")
print("Initial stack: " + str(stack))
print("pop(): " + str(stack.pop()))
print("After pop(), the stack is now: " + str(stack))
print("peek(): " + str(stack.peek()))
assert stack.is_full()
assert str(stack) == str([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
assert stack.pop() == 9
assert stack.peek() == 8

stack.push(100)
print("After push(100), the stack is now: " + str(stack))
print("is_empty(): " + str(stack.is_empty()))
print("size(): " + str(stack.size()))
assert str(stack) == str([0, 1, 2, 3, 4, 5, 6, 7, 8, 100])

assert not stack.is_empty()
assert stack.size() == 10

num = 5
if num in stack:
print(f"{num} is in stack")
assert num in stack
num = 55
assert num not in stack