|
| 1 | +import os |
| 2 | + |
| 3 | +class Stacks: |
| 4 | + def __init__(self): |
| 5 | + ''' |
| 6 | + Initialises a empty list which will be used as Stack array. |
| 7 | + ''' |
| 8 | + self._data = [] |
| 9 | + |
| 10 | + def __len__(self): |
| 11 | + ''' |
| 12 | + Returns length of Stack> |
| 13 | + ''' |
| 14 | + return len(self._data) |
| 15 | + |
| 16 | + def isempty(self): |
| 17 | + ''' |
| 18 | + Returns True if stack is empty, else False. |
| 19 | + ''' |
| 20 | + return len(self._data) == 0 |
| 21 | + |
| 22 | + def push(self, e): |
| 23 | + ''' |
| 24 | + Pushes the passed element(e) on the stack. |
| 25 | + ''' |
| 26 | + self._data.append(e) |
| 27 | + |
| 28 | + def pop(self): |
| 29 | + ''' |
| 30 | + Removes the element on the top and returns it. |
| 31 | + ''' |
| 32 | + if self.isempty(): |
| 33 | + print("Stack is Empty") |
| 34 | + return |
| 35 | + |
| 36 | + return self._data.pop() |
| 37 | + |
| 38 | + def top(self): |
| 39 | + ''' |
| 40 | + Peeks at the element on the top of the stack. |
| 41 | + ''' |
| 42 | + if self.isempty(): |
| 43 | + print("Stack is Empty") |
| 44 | + return |
| 45 | + |
| 46 | + return self._data[-1] |
| 47 | + |
| 48 | + def display(self): |
| 49 | + ''' |
| 50 | + Utility function to display the stack. |
| 51 | + ''' |
| 52 | + if self.isempty(): |
| 53 | + print("Stack is Empty") |
| 54 | + return |
| 55 | + print("Stack:") |
| 56 | + for item in reversed(self._data): |
| 57 | + print(item) |
| 58 | + |
| 59 | +############################################################################### |
| 60 | + |
| 61 | +def options(): |
| 62 | + ''' |
| 63 | + Prints Menu for operations |
| 64 | + ''' |
| 65 | + options_list = ['Push', 'Pop', 'Top', |
| 66 | + 'Display Stack', 'Exit'] |
| 67 | + |
| 68 | + print("MENU") |
| 69 | + for i, option in enumerate(options_list): |
| 70 | + print(f'{i + 1}. {option}') |
| 71 | + |
| 72 | + choice = int(input("Enter choice: ")) |
| 73 | + return choice |
| 74 | + |
| 75 | +def switch_case(choice): |
| 76 | + ''' |
| 77 | + Switch Case for operations |
| 78 | + ''' |
| 79 | + os.system('cls') |
| 80 | + if choice == 1: |
| 81 | + elem = int(input("Enter Item: ")) |
| 82 | + S.push(elem) |
| 83 | + |
| 84 | + elif choice == 2: |
| 85 | + print('Popped item is: ', S.pop()) |
| 86 | + |
| 87 | + elif choice == 3: |
| 88 | + print("Item on top is: ", S.top()) |
| 89 | + |
| 90 | + elif choice == 4: |
| 91 | + print("Stack: ", end='') |
| 92 | + S.display() |
| 93 | + print("\n") |
| 94 | + |
| 95 | + elif choice == 5: |
| 96 | + import sys |
| 97 | + sys.exit() |
| 98 | + |
| 99 | +############################################################################### |
| 100 | + |
| 101 | +S = Stacks() |
| 102 | +while True: |
| 103 | + choice = options() |
| 104 | + switch_case(choice) |
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