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Add type hints to binary_tree_traversals.py (#1123)

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Christian Clauss 2019-08-12 17:59:59 +02:00 committed by GitHub
parent 158b319d22
commit 4fea48072a
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1 changed files with 50 additions and 53 deletions
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103
traversals/binary_tree_traversals.py
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@ -1,14 +1,8 @@
""" """
This is pure python implementation of tree traversal algorithms This is pure python implementation of tree traversal algorithms
""" """
from __future__ import print_function
import queue import queue
from typing import List
try:
raw_input # Python 2
except NameError:
raw_input = input # Python 3
class TreeNode: class TreeNode:
@ -20,35 +14,31 @@ class TreeNode:
def build_tree(): def build_tree():
print("\n********Press N to stop entering at any point of time********\n") print("\n********Press N to stop entering at any point of time********\n")
print("Enter the value of the root node: ", end="") check = input("Enter the value of the root node: ").strip().lower() or "n"
check = raw_input().strip().lower() if check == "n":
if check == 'n':
return None return None
data = int(check) q: queue.Queue = queue.Queue()
q = queue.Queue() tree_node = TreeNode(int(check))
tree_node = TreeNode(data)
q.put(tree_node) q.put(tree_node)
while not q.empty(): while not q.empty():
node_found = q.get() node_found = q.get()
print("Enter the left node of %s: " % node_found.data, end="") msg = "Enter the left node of %s: " % node_found.data
check = raw_input().strip().lower() check = input(msg).strip().lower() or "n"
if check == 'n': if check == "n":
return tree_node return tree_node
left_data = int(check) left_node = TreeNode(int(check))
left_node = TreeNode(left_data)
node_found.left = left_node node_found.left = left_node
q.put(left_node) q.put(left_node)
print("Enter the right node of %s: " % node_found.data, end="") msg = "Enter the right node of %s: " % node_found.data
check = raw_input().strip().lower() check = input(msg).strip().lower() or "n"
if check == 'n': if check == "n":
return tree_node return tree_node
right_data = int(check) right_node = TreeNode(int(check))
right_node = TreeNode(right_data)
node_found.right = right_node node_found.right = right_node
q.put(right_node) q.put(right_node)
def pre_order(node): def pre_order(node: TreeNode) -> None:
if not isinstance(node, TreeNode) or not node: if not isinstance(node, TreeNode) or not node:
return return
print(node.data, end=" ") print(node.data, end=" ")
@ -56,7 +46,7 @@ def pre_order(node):
pre_order(node.right) pre_order(node.right)
def in_order(node): def in_order(node: TreeNode) -> None:
if not isinstance(node, TreeNode) or not node: if not isinstance(node, TreeNode) or not node:
return return
in_order(node.left) in_order(node.left)
@ -64,7 +54,7 @@ def in_order(node):
in_order(node.right) in_order(node.right)
def post_order(node): def post_order(node: TreeNode) -> None:
if not isinstance(node, TreeNode) or not node: if not isinstance(node, TreeNode) or not node:
return return
post_order(node.left) post_order(node.left)
@ -72,10 +62,10 @@ def post_order(node):
print(node.data, end=" ") print(node.data, end=" ")
def level_order(node): def level_order(node: TreeNode) -> None:
if not isinstance(node, TreeNode) or not node: if not isinstance(node, TreeNode) or not node:
return return
q = queue.Queue() q: queue.Queue = queue.Queue()
q.put(node) q.put(node)
while not q.empty(): while not q.empty():
node_dequeued = q.get() node_dequeued = q.get()
@ -86,10 +76,10 @@ def level_order(node):
q.put(node_dequeued.right) q.put(node_dequeued.right)
def level_order_actual(node): def level_order_actual(node: TreeNode) -> None:
if not isinstance(node, TreeNode) or not node: if not isinstance(node, TreeNode) or not node:
return return
q = queue.Queue() q: queue.Queue = queue.Queue()
q.put(node) q.put(node)
while not q.empty(): while not q.empty():
list = [] list = []
@ -106,10 +96,10 @@ def level_order_actual(node):
# iteration version # iteration version
def pre_order_iter(node): def pre_order_iter(node: TreeNode) -> None:
if not isinstance(node, TreeNode) or not node: if not isinstance(node, TreeNode) or not node:
return return
stack = [] stack: List[TreeNode] = []
n = node n = node
while n or stack: while n or stack:
while n: # start from root node, find its left child while n: # start from root node, find its left child
@ -122,10 +112,10 @@ def pre_order_iter(node):
n = n.right n = n.right
def in_order_iter(node): def in_order_iter(node: TreeNode) -> None:
if not isinstance(node, TreeNode) or not node: if not isinstance(node, TreeNode) or not node:
return return
stack = [] stack: List[TreeNode] = []
n = node n = node
while n or stack: while n or stack:
while n: while n:
@ -136,7 +126,7 @@ def in_order_iter(node):
n = n.right n = n.right
def post_order_iter(node): def post_order_iter(node: TreeNode) -> None:
if not isinstance(node, TreeNode) or not node: if not isinstance(node, TreeNode) or not node:
return return
stack1, stack2 = [], [] stack1, stack2 = [], []
@ -153,38 +143,45 @@ def post_order_iter(node):
print(stack2.pop().data, end=" ") print(stack2.pop().data, end=" ")
if __name__ == '__main__': def prompt(s: str = "", width=50, char="*") -> str:
print("\n********* Binary Tree Traversals ************\n") if not s:
return "\n" + width * char
left, extra = divmod(width - len(s) - 2, 2)
return f"{left * char} {s} {(left + extra) * char}"
if __name__ == "__main__":
print(prompt("Binary Tree Traversals"))
node = build_tree() node = build_tree()
print("\n********* Pre Order Traversal ************") print(prompt("Pre Order Traversal"))
pre_order(node) pre_order(node)
print("\n******************************************\n") print(prompt() + "\n")
print("\n********* In Order Traversal ************") print(prompt("In Order Traversal"))
in_order(node) in_order(node)
print("\n******************************************\n") print(prompt() + "\n")
print("\n********* Post Order Traversal ************") print(prompt("Post Order Traversal"))
post_order(node) post_order(node)
print("\n******************************************\n") print(prompt() + "\n")
print("\n********* Level Order Traversal ************") print(prompt("Level Order Traversal"))
level_order(node) level_order(node)
print("\n******************************************\n") print(prompt() + "\n")
print("\n********* Actual Level Order Traversal ************") print(prompt("Actual Level Order Traversal"))
level_order_actual(node) level_order_actual(node)
print("\n******************************************\n") print("*" * 50 + "\n")
print("\n********* Pre Order Traversal - Iteration Version ************") print(prompt("Pre Order Traversal - Iteration Version"))
pre_order_iter(node) pre_order_iter(node)
print("\n******************************************\n") print(prompt() + "\n")
print("\n********* In Order Traversal - Iteration Version ************") print(prompt("In Order Traversal - Iteration Version"))
in_order_iter(node) in_order_iter(node)
print("\n******************************************\n") print(prompt() + "\n")
print("\n********* Post Order Traversal - Iteration Version ************") print(prompt("Post Order Traversal - Iteration Version"))
post_order_iter(node) post_order_iter(node)
print("\n******************************************\n") print(prompt())