Problem:
Binary Search Tree I Search trees are data structures that support dynamic set operations including insert, search, delete and so on. Thus a search tree can be used both as a dictionary and as a priority queue. Binary search tree is one of fundamental search trees. The keys in a binary search tree are always stored in such a way as to satisfy the following binary search tree property:  Let $x$ be a node in a binary search tree. If $y$ is a node in the left subtree of $x$, then $y.key \leq x.key$. If $y$ is a node in the right subtree of $x$, then $x.key \leq y.key$.  The following figure shows an example of the binary search tree.   For example, keys of nodes which belong to the left sub-tree of the node containing 80 are less than or equal to 80, and keys of nodes which belong to the right sub-tree are more than or equal to 80. The binary search tree property allows us to print out all the keys in the tree in sorted order by an inorder tree walk. A binary search tree should be implemented in such a way that the binary search tree property continues to hold after modifications by insertions and deletions. A binary search tree can be represented by a linked data structure in which each node is an object. In addition to a key field and satellite data, each node contains fields left , right , and p that point to the nodes corresponding to its left child, its right child, and its parent, respectively. To insert a new value $v$ into a binary search tree $T$, we can use the procedure insert as shown in the following pseudo code. The insert procedure is passed a node $z$ for which $z.key = v$, $z.left = NIL$, and $z.right = NIL$. The procedure modifies $T$ and some of the fields of $z$ in such a way that $z$ is inserted into an appropriate position in the tree. 1 insert(T, z)
2     y = NIL // parent of x
3     x = 'the root of T'
4     while x ≠ NIL
5         y = x // set the parent
6         if z.key < x.key
7             x = x.left // move to the left child
8         else 
9             x = x.right // move to the right child
10    z.p = y
11
12    if y == NIL // T is empty
13        'the root of T' = z
14    else if z.key < y.key
15        y.left = z // z is the left child of y
16    else 
17        y.right = z // z is the right child of y Write a program which performs the following operations to a binary search tree $T$.  insert $k$: Insert a node containing $k$ as key into $T$.  print : Print the keys of the binary search tree by inorder tree walk and  preorder tree walk respectively.  You should use the above pseudo code to implement the insert operation. $T$ is empty at the initial state. Input In the first line, the number of operations $m$ is given. In the following $m$ lines, operations represented by insert $k$ or print are given. Output For each print operation, print a list of keys obtained by inorder tree walk and preorder tree walk in a line respectively. Put a space character before each key . Constraints  The number of operations $\leq 500,000$  The number of print operations $\leq 10$.  $-2,000,000,000 \leq key \leq 2,000,000,000$  The height of the binary tree does not exceed 100 if you employ the above pseudo code.  The keys in the binary search tree are all different.  Sample Input 1 8
insert 30
insert 88
insert 12
insert 1
insert 20
insert 17
insert 25
print Sample Output 1 1 12 17 20 25 30 88
 30 12 1 20 17 25 88 Reference Introduction to Algorithms, Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, and Clifford Stein. The MIT Press.

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

class BST:
    def __init__(self):
        self.root = None
    def insert(self, key):
        x, y = self.root, None
        while x != None: x, y = x.left if key < x.key else x.right, x
        if y == None: self.root = Node(key)
        elif key < y.key: y.left = Node(key)
        else: y.right = Node(key)
    def print_tree(self):
        def inorder(node):
            return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
        def preorder(node):
            return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''
        print(inorder(self.root))
        print(preorder(self.root))

tree = BST()
input()
for e in sys.stdin:
    if e[0] == 'i': tree.insert(int(e[7:]))
    else: tree.print_tree()

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

class BST:
    def __init__(self):
        self.root = None
    def insert(self, key):
        x, y = self.root, None
        while x != None: x, y = x.left if key < x.key else x.right, x
        if y == None: self.root = Node(key)
        elif key < y.key: y.left = Node(key)
        else: y.right = Node(key)
    def print_tree(self):
        def inorder(node):
            return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
        def preorder(node):
            return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''
        print(inorder(self.root))
        print(preorder(self.root))

tree = BST()
input()
for e in sys.stdin:
    if e[0] == 'i': tree.insert(int(e[7:]))
    else: tree.print_tree()

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

class BST:
    def __init__(self):
        self.root = None
    def insert(self, key):
        x, y = self.root, None
        while x != None: x, y = x.left if key < x.key else x.right, x
        if y == None: self.root = Node(key)
        elif key < y.key: y.left = Node(key)
        else: y.right = Node(key)
    def print_tree(self):
        def inorder(node):
            return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
        def preorder(node):
            return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''
        print(inorder(self.root))
        print(preorder(self.root))

tree = BST()
input()
for e in sys.stdin:
    if e[0] == 'i': tree.insert(int(e[7:]))
    else: tree.print_tree()

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x != None: x, y = x.left if key < x.key else x.right, x
    if y == None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else:
        print(inorder(root))
        print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x != None: x, y = x.left if key < x.key else x.right, x
    if y == None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else:
        print(inorder(root))
        print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x != None: x, y = x.left if key < x.key else x.right, x
    if y == None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else:
        print(inorder(root))
        print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x != None: x, y = x.left if key < x.key else x.right, x
    if y == None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x != None: x, y = x.left if key < x.key else x.right, x
    if y == None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x != None: x, y = x.left if key < x.key else x.right, x
    if y == None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x != None: x, y = x.left if key < x.key else x.right, x
    if y == None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
import sys

class Node:
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

class BST:
    def __init__(self):
        self.root = None
    def insert(self, key):
        x, y = self.root, None
        while x != None: x, y = x.left if key < x.key else x.right, x
        if y == None: self.root = Node(key)
        elif key < y.key: y.left = Node(key)
        else: y.right = Node(key)
    def print_tree(self):
        def inorder(node):
            return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
        def preorder(node):
            return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''
        print(inorder(self.root))
        print(preorder(self.root))

tree = BST()
input()
for e in sys.stdin:
    if e[0] == 'i': tree.insert(int(e[7:]))
    else: tree.print_tree()

Solution (Python):
import sys

class Node:
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

class BST:
    def __init__(self):
        self.root = None
    def insert(self, key):
        x, y = self.root, None
        while x != None: x, y = x.left if key < x.key else x.right, x
        if y == None: self.root = Node(key)
        elif key < y.key: y.left = Node(key)
        else: y.right = Node(key)
    def print_tree(self):
        def inorder(node):
            return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
        def preorder(node):
            return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''
        print(inorder(self.root))
        print(preorder(self.root))

tree = BST()
input()
for e in sys.stdin:
    if e[0] == 'i': tree.insert(int(e[7:]))
    else: tree.print_tree()

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

class BST:
    __slots__ = ['root']
    def __init__(self):
        self.root = None
    def insert(self, key):
        x, y = self.root, None
        while x != None: x, y = x.left if key < x.key else x.right, x
        if y == None: self.root = Node(key)
        elif key < y.key: y.left = Node(key)
        else: y.right = Node(key)
    def print_tree(self):
        def inorder(node):
            return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
        def preorder(node):
            return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''
        print(inorder(self.root))
        print(preorder(self.root))

tree = BST()
input()
for e in sys.stdin:
    if e[0] == 'i': tree.insert(int(e[7:]))
    else: tree.print_tree()

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

class BST:
    __slots__ = ['root']
    def __init__(self):
        self.root = None
    def insert(self, key):
        x, y = self.root, None
        while x != None: x, y = x.left if key < x.key else x.right, x
        if y == None: self.root = Node(key)
        elif key < y.key: y.left = Node(key)
        else: y.right = Node(key)
    def print_tree(self):
        def inorder(node):
            return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
        def preorder(node):
            return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''
        print(inorder(self.root))
        print(preorder(self.root))

tree = BST()
input()
for e in sys.stdin:
    if e[0] == 'i': tree.insert(int(e[7:]))
    else: tree.print_tree()

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x is not None: x, y = x.left if key < x.key else x.right, x
    if y is None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x is not None: x, y = x.left if key < x.key else x.right, x
    if y is None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x is not None: x, y = x.left if key < x.key else x.right, x
    if y is None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x is not None: x, y = x.left if key < x.key else x.right, x
    if y is None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x is not None: x, y = x.left if key < x.key else x.right, x
    if y is None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
import sys

class Node:
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left = self.right = None

root = None

def insert(key):
    global root
    x, y = root, None
    while x: x, y = x.left if key < x.key else x.right, x
    if y is None: root = Node(key)
    elif key < y.key: y.left = Node(key)
    else: y.right = Node(key)

def inorder(node):
    return inorder(node.left) + f' {node.key}' + inorder(node.right) if node else ''
def preorder(node):
    return f' {node.key}' + preorder(node.left) + preorder(node.right) if node else ''

input()
for e in sys.stdin:
    if e[0] == 'i': insert(int(e[7:]))
    else: print(inorder(root)); print(preorder(root))

Solution (Python):
class Tree():
    def __init__(self):
        self.root = None
    def insert(self, key):
        z = Node(key)
        y = None
        x = self.root
        while x:
            y = x
            if z.key < x.key:
                x = x.left
            else:
                x = x.right
        z.parent = y
        if y == None:
            self.root = z
        elif z.key < y.key:
            y.left = z
        else:
            y.right = z

    def print(self):
        print('', ' '.join(map(str, self.root.inwalk())))
        print('', ' '.join(map(str, self.root.prewalk())))


class Node():
    def __init__(self, key):
        self.key = key
        self.parent = self.left = self.right = None

    def prewalk(self):
        ret = [self.key]
        if self.left:
            ret += self.left.prewalk()
        if self.right:
            ret += self.right.prewalk()
        return ret

    def inwalk(self):
        ret = []
        if self.left:
            ret += self.left.inwalk()
        ret += [self.key]
        if self.right:
            ret += self.right.inwalk()
        return ret


tree = Tree()
n = int(input())
for i in range(n):
    com = input().split()
    if len(com) == 2:
        tree.insert(int(com[1]))
    else:
        tree.print()

Solution (Python):

class Node:
    def __init__(self, v):
        self.value = v
        self.parent = None
        self.left = None
        self.right = None


def insert_(node, x):
    if node is None:
        return Node(x)
    elif x == node.value:
        return node
    elif x < node.value:
        node.left = insert(node.left, x)
    else:
        node.right = insert(node.right, x)
    return node


def insert(node):
    global root
    y = None
    x = root
    while x is not None:
        y = x
        if node.value < x.value:
            x = x.left
        else:
            x = x.right
    node.parent = y
    if y is None:
        root = node
    elif node.value < y.value:
        y.left = node
    else:
        y.right = node

def preorder_walk(node):
    if node:
        yield node.value
        for x in preorder_walk(node.left):
            yield x
        for x in preorder_walk(node.right):
            yield x

def inorder_walk(node):
    if node:
        for x in inorder_walk(node.left):
            yield x
        yield node.value
        for x in inorder_walk(node.right):
            yield x

root = None
n = int(input())
for i in range(n):
    cmd, *val = input().split()
    if cmd == "insert":
        
        insert(Node(int(val[0])))
    elif cmd == "print":
        print("", *inorder_walk(root))
        print("", *preorder_walk(root))

Solution (Python):
import sys


class BinarySearchTree:
    class Node:
        def __init__(self, value):
            self.value = value
            self.left = None
            self.right = None

        def has_left(self):
            return self.left is not None

        def has_right(self):
            return self.right is not None

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

    def __init__(self):
        self.root = None

    def insert(self, value):
        if self.root is None:
            self.root = self.Node(value)
            return

        node = self.root
        while True:
            if node.value > value:
                if node.has_left():
                    node = node.left
                else:
                    node.left = self.Node(value)
                    break
            else:
                if node.has_right():
                    node = node.right
                else:
                    node.right = self.Node(value)
                    break

    def preorder(self):
        def _preorder(node):
            yield node
            if node.has_left():
                yield from _preorder(node.left)
            if node.has_right():
                yield from _preorder(node.right)
        if self.root is not None:
            yield from _preorder(self.root)

    def inorder(self):
        def _inorder(node):
            if node.has_left():
                yield from _inorder(node.left)
            yield node
            if node.has_right():
                yield from _inorder(node.right)
        if self.root is not None:
            yield from _inorder(self.root)

    def postorder(self):
        def _postorder(node):
            if node.has_left():
                yield from _postorder(node.left)
            if node.has_right():
                yield from _postorder(node.right)
            yield node
        if self.root is not None:
            yield from _postorder(self.root)


def run():
    _ = int(input())
    tree = BinarySearchTree()

    for line in sys.stdin:
        command = line.split()
        if command[0] == 'insert':
            tree.insert(int(command[1]))
        elif command[0] == 'print':
            inorder = ''
            for node in tree.inorder():
                inorder += " {}".format(node)
            print(inorder)
            preorder = ''
            for node in tree.preorder():
                preorder += " {}".format(node)
            print(preorder)
        else:
            raise ValueError('invalid command')


if __name__ == '__main__':
    run()

Solution (Python):
import copy
class Node():
    def __init__(self, parent = -1, left = -1, right = -1):
        self.parent = parent
        self.left = left
        self.right = right
        
    def __eq__(self, other):
        if self.num == other.num:
            return True
        else:
            return False

def insert(node, z):
    global root
    p = -1
    x = root
    while x != -1:
        p = x
        if z < x:
            x = node[x].left
        else:
            x = node[x].right
    
    if p == -1:
        root = z
        node[z] = Node()
    elif z < p:
        node[p].left = z
        node[z] = Node(p)
    else:
        node[p].right = z
        node[z] = Node(p)
        
def preorder(node, i):
    print(" " + str(i), end ="")
    if node[i].left != -1:
        preorder(node, node[i].left)
    if node[i].right != -1:
        preorder(node, node[i].right)

def inorder(node, i):
    if node[i].left != -1:
        inorder(node, node[i].left)
    print(" " + str(i), end ="")
    if node[i].right != -1:
        inorder(node, node[i].right)
        
n = int(input())
node = {}
root = -1
for i in range(n):
    s = input()
    if s == "print":
        inorder(node, root)
        print()
        preorder(node, root)
        print()
    else:
        s = s.split()
        insert(node, int(s[1]))

Solution (Python):
import sys

class Node():
    def __init__(self, parent = -1, left = -1, right = -1):
        self.parent = parent
        self.left = left
        self.right = right
        
    def __eq__(self, other):
        if self.num == other.num:
            return True
        else:
            return False

def insert(node, z):
    global root
    p = -1
    x = root
    while x != -1:
        p = x
        if z < x:
            x = node[x].left
        else:
            x = node[x].right
    
    if p == -1:
        root = z
        node[z] = Node()
    elif z < p:
        node[p].left = z
        node[z] = Node(p)
    else:
        node[p].right = z
        node[z] = Node(p)
        
def preorder(node, i):
    print(" " + str(i), end ="")
    if node[i].left != -1:
        preorder(node, node[i].left)
    if node[i].right != -1:
        preorder(node, node[i].right)

def inorder(node, i):
    if node[i].left != -1:
        inorder(node, node[i].left)
    print(" " + str(i), end ="")
    if node[i].right != -1:
        inorder(node, node[i].right)
        
input()
node = {}
root = -1
for s in sys.stdin:
    if s[0] == "p":
        inorder(node, root)
        print()
        preorder(node, root)
        print()
    else:
        insert(node, int(s[7:]))

Solution (Python):
import sys

class Node():
    __slots__ = ['key', 'left', 'right']
    def __init__(self, key):
        self.key = key
        self.left, self.right = None, None
        
    def __str__(self):
        return self.key

root = None
def insert(z):
    global root
    x, y = root, None
    while x:
        y = x
        if z < x.key:
            x = x.left
        else:
            x = x.right
    
    if y == None:
        root = Node(z)
    elif z < y.key:
        y.left = Node(z)
    else:
        y.right = Node(z)
        
def preorder(x):
    return f" {x.key}" + preorder(x.left) + preorder(x.right) if x else ""

def inorder(x):
    return inorder(x.left) + f" {x.key}" + inorder(x.right) if x else ""
        
input()
node = {}
for s in sys.stdin:
    if s[0] == "p":
        pass
        print(inorder(root))
        print(preorder(root))
    else:
        insert(int(s[7:]))

Solution (Python):
class BinaryTreeNode():
    
    def __init__(self, left=None, right=None, val=None):
        self.left = left
        self.right = right
        self.val = val

class BinarySearchTree():
    def __init__(self):
        self.root = None

    def insert(self, val):
        y = None
        x = self.root
        while x != None:
            y = x
            if val < x.val:
                x = x.left
            else:
                x = x.right
        node = BinaryTreeNode(val=val)

        if y == None:
            self.root = node
        elif node.val < y.val:
            y.left = node
        else:
            y.right = node

    def preorder(self):
        self.preorder_list = []
        self.preorder_bfs(self.root)
        return self.preorder_list

    def preorder_bfs(self, u):
        if u == None: return
        self.preorder_list.append(u.val)
        self.preorder_bfs(u.left)
        self.preorder_bfs(u.right)

    def inorder(self):
        self.inorder_list = []
        self.inorder_dfs(self.root)
        return self.inorder_list

    def inorder_dfs(self, u):
        if u == None: return
        self.inorder_dfs(u.left)
        self.inorder_list.append(u.val)
        self.inorder_dfs(u.right)

def print_elements(arr):
    print(' ' + ' '.join([str(item) for item in arr]))

m = int(input())
bst = BinarySearchTree()
for i in range(m):
    op = input()
    if op == 'print':
        print_elements(bst.inorder())
        print_elements(bst.preorder())
    else:
        num = int(op[7:])
        bst.insert(num)

Solution (Python):
class Node:
    def __init__(self, key=-1, parent=-1, left=-1, right=-1):
        self.key = key
        self.parent = parent
        self.left = left
        self.right = right


def insert(t, z):
    x, y = t, -1
    while x != -1:
        y = x
        if z.key < x.key:
            x = x.left
        else:
            x = x.right
    z.parent = y

    if y == -1:
        t = z
    elif z.key < y.key:
        y.left = z
    else:
        y.right = z

    return t


def print_tree(t):
    def in_order(z):
        if z == -1:
            return

        in_order(z.left)
        print(" {}".format(z.key), end="")
        in_order(z.right)

    def pre_order(z):
        if z == -1:
            return

        print(" {}".format(z.key), end="")
        pre_order(z.left)
        pre_order(z.right)

    in_order(t)
    print()
    pre_order(t)
    print()


def main():
    n = int(input())
    bst = -1

    for i in range(n):
        order = input().split()
        if order[0][0] == "i":
            node = Node(key=int(order[1]))
            bst = insert(bst, node)
        else:
            print_tree(bst)


if __name__ == '__main__':
    main()