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| 1 | +class Heap: |
| 2 | + def __init__(self, maxsize): |
| 3 | + ''' |
| 4 | + Initialises the size of heap using maxsize parameter passed by users. |
| 5 | + ''' |
| 6 | + self._maxsize = maxsize |
| 7 | + self._heap = [-1] * (self._maxsize + 1) |
| 8 | + self._size = 0 |
| 9 | + |
| 10 | + def __len__(self): |
| 11 | + ''' |
| 12 | + Returns the size of heap. |
| 13 | + ''' |
| 14 | + return self._size |
| 15 | + |
| 16 | + def isempty(self): |
| 17 | + ''' |
| 18 | + Returns True if heap is empty, else False. |
| 19 | + ''' |
| 20 | + return self._size == 0 |
| 21 | + |
| 22 | + def insert(self, e): |
| 23 | + ''' |
| 24 | + Insertion Operation. |
| 25 | + ''' |
| 26 | + if self._size == self._maxsize: |
| 27 | + print(f"Max {self._maxsize} elements can be inserted !") |
| 28 | + else: |
| 29 | + self._size += 1 |
| 30 | + hi = self._size |
| 31 | + |
| 32 | + # while child > parent |
| 33 | + while e > self._heap[hi//2] and hi > 1: |
| 34 | + self._heap[hi] = self._heap[hi//2] |
| 35 | + hi = hi//2 |
| 36 | + self._heap[hi] = e |
| 37 | + |
| 38 | + def max(self): |
| 39 | + ''' |
| 40 | + Returns the maximum element from the heap. |
| 41 | + ''' |
| 42 | + return self._heap[1] |
| 43 | + |
| 44 | + def deleteMax(self): |
| 45 | + ''' |
| 46 | + Deletes the maximum element from the heap. |
| 47 | + ''' |
| 48 | + root = self._heap[1] |
| 49 | + self._heap[1] = self._heap[self._size] |
| 50 | + self._heap[self._size] = -1 |
| 51 | + self._size -= 1 |
| 52 | + |
| 53 | + i = 1 |
| 54 | + j = i * 2 |
| 55 | + while j <= self._size: |
| 56 | + if self._heap[j] < self._heap[j + 1]: |
| 57 | + j = j + 1 |
| 58 | + if self._heap[i] < self._heap[j]: |
| 59 | + self._heap[i], self._heap[j] = self._heap[j], self._heap[i] |
| 60 | + i = j |
| 61 | + j = i * 2 |
| 62 | + else: |
| 63 | + break |
| 64 | + return root |
| 65 | + |
| 66 | + def display(self): |
| 67 | + ''' |
| 68 | + Utility function to display the heap. |
| 69 | + ''' |
| 70 | + if self.isempty(): |
| 71 | + print("Heap is empty !") |
| 72 | + else: |
| 73 | + print("Heap: ", end='') |
| 74 | + for i in range(1, self._size + 1): |
| 75 | + print(self._heap[i], end=" ") |
| 76 | + |
| 77 | + |
| 78 | +def options(): |
| 79 | + ''' |
| 80 | + Prints Menu for operations |
| 81 | + ''' |
| 82 | + options_list = ['Insert an item', 'Insert multiple items', |
| 83 | + 'Max', 'Delete Max', 'Display', 'Exit'] |
| 84 | + |
| 85 | + print("\nMENU") |
| 86 | + for i, option in enumerate(options_list): |
| 87 | + print(f'{i + 1}. {option}') |
| 88 | + |
| 89 | + choice = int(input("Enter choice: ")) |
| 90 | + return choice |
| 91 | + |
| 92 | +############################################################################### |
| 93 | + |
| 94 | + |
| 95 | +def switch_case(choice): |
| 96 | + ''' |
| 97 | + Switch Case for operations |
| 98 | + ''' |
| 99 | + # os.system('cls') |
| 100 | + if choice == 1: |
| 101 | + elem = int(input("Enter an Item: ")) |
| 102 | + hp.insert(elem) |
| 103 | + elif choice == 2: |
| 104 | + A = list(map(int, input("Enter items: ").split())) |
| 105 | + for elem in A: |
| 106 | + hp.insert(elem) |
| 107 | + |
| 108 | + elif choice == 3: |
| 109 | + print("Max element is: ", hp.max()) |
| 110 | + |
| 111 | + elif choice == 4: |
| 112 | + print("Deleted element is: ", hp.deleteMax()) |
| 113 | + |
| 114 | + elif choice == 5: |
| 115 | + hp.display() |
| 116 | + |
| 117 | + elif choice == 6: |
| 118 | + import sys |
| 119 | + sys.exit() |
| 120 | + |
| 121 | +############################################################################### |
| 122 | + |
| 123 | + |
| 124 | +if __name__ == '__main__': |
| 125 | + hp = Heap(10) |
| 126 | + while True: |
| 127 | + choice = options() |
| 128 | + switch_case(choice) |
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