Python Program to Implement Ternary Heap

class TernaryHeap:
    def __init__(self):
        self.items = []
 
    def size(self):
        return len(self.items)
 
    def parent(self, i):
        return (i - 1)//3
 
    def left(self, i):
        return 3*i + 1
 
    def mid(self, i):
        return 3*i + 2
 
    def right(self, i):
        return 3*i + 3
 
    def get(self, i):
        return self.items[i]
 
    def get_max(self):
        if self.size() == 0:
            return None
        return self.items[0]
 
    def extract_max(self):
        if self.size() == 0:
            return None
        largest = self.get_max()
        self.items[0] = self.items[-1]
        del self.items[-1]
        self.max_heapify(0)
        return largest
 
    def max_heapify(self, i):
        l = self.left(i)
        r = self.right(i)
        m = self.mid(i)
        if (l <= self.size() - 1 and self.get(l) > self.get(i)):
            largest = l
        else:
            largest = i
        if (m <= self.size() - 1 and self.get(m) > self.get(largest)):
            largest = m
        if (r <= self.size() - 1 and self.get(r) > self.get(largest)):
            largest = r
        if (largest != i):
            self.swap(largest, i)
            self.max_heapify(largest)
 
    def swap(self, i, j):
        self.items[i], self.items[j] = self.items[j], self.items[i]
 
    def insert(self, key):
        index = self.size()
        self.items.append(key)
 
        while (index != 0):
            p = self.parent(index)
            if self.get(p) < self.get(index):
                self.swap(p, index)
            index = p
 
 
theap = TernaryHeap()
 
print('Menu (this assumes no duplicate keys)')
print('insert <data>')
print('max get')
print('max extract')
print('quit')
 
while True:
    do = input('What would you like to do? ').split()
 
    operation = do[0].strip().lower()
    if operation == 'insert':
        data = int(do[1])
        theap.insert(data)
    elif operation == 'max':
        suboperation = do[1].strip().lower()
        if suboperation == 'get':
            print('Maximum value: {}'.format(theap.get_max()))
        elif suboperation == 'extract':
            print('Maximum value removed: {}'.format(theap.extract_max()))
 
    elif operation == 'quit':
        break

Output

Menu (this assumes no duplicate keys)
insert <data>
max get
max extract
quit
What would you like to do? insert 3
What would you like to do? insert 1
What would you like to do? insert 7
What would you like to do? max extract
Maximum value removed: 7
What would you like to do? max extract
Maximum value removed: 3
What would you like to do? max extract
Maximum value removed: 1
What would you like to do? max extract
Maximum value removed: None
What would you like to do? quit