class HeapArray:

    def __init__(self):
        self._data = []
        self._size = 0

    def __str__(self):
        return str(self._data)

    def is_empty(self):
        return self._size == 0

    def insert(self,num):
        index = self._size
        self._data.insert(index,num) #cound have used .append(num)
        while index > 0 and self._data[index] < self._data[(index-1)//2]:
            temp = self._data[index]
            self._data[index] = self._data[(index-1)//2]
            self._data[(index-1)//2] = temp
            index = (index-1)//2
        self._size = self._size + 1

    def delete_min(self):
        if self._size == 0:
            return None
        elif self._size == 1:
            self._size = 0
            return self._data.pop(0)
        else:
            min = self._data[0]
            self._data[0] = self._data.pop(self._size-1)
            self._size = self._size - 1
            index = 0
            while 2*index+1 < self._size:
                if 2*index+2 < self._size: # 2 children
                    if self._data[index] < self._data[2*index+1] and \
                       self._data[index] < self._data[2*index+2]:
                        break
                    if self._data[2*index+1] < self._data[2*index+2]:
                        temp = self._data[index]
                        self._data[index] = self._data[2*index+1]
                        self._data[2*index+1] = temp
                        index = 2*index+1
                    else:
                        temp = self._data[index]
                        self._data[index] = self._data[2*index+2]
                        self._data[2*index+2] = temp
                        index = 2*index+2
                else: # one child
                    if self._data[index] > self._data[2*index+1]:
                        temp = self._data[index]
                        self._data[index] = self._data[2*index+1]
                        self._data[2*index+1] = temp
                        index = 2*index+1
                    else:
                        break
            return min
            
    

pq = HeapArray()

pq.insert(10)
pq.insert(5)
pq.insert(12)
pq.insert(8)

print(pq)

[5, 8, 12, 10]

x = pq.delete_min()

print(x)

5

print(pq)

[8, 10, 12]