Commit 6f28333

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Adding function for actual level order traversal (TheAlgorithms#699)

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traversals
- binary_tree_traversals.py

1 file changed

+39

-9

lines changed

`‎traversals/binary_tree_traversals.py`

Lines changed: 39 additions & 9 deletions

Original file line number	Diff line number	Diff line change
`@@ -2,10 +2,11 @@`
`2`	`2`	`This is pure python implementation of tree traversal algorithms`
`3`	`3`	`"""`
`4`	`4`	`from __future__ import print_function`
	`5`	`+`
`5`	`6`	`import queue`
`6`	`7`
`7`	`8`	`try:`
`8`		`- raw_input # Python 2`
	`9`	`+ raw_input # Python 2`
`9`	`10`	`except NameError:`
`10`	`11`	`raw_input = input # Python 3`
`11`	`12`
`@@ -22,7 +23,7 @@ def build_tree():`
`22`	`23`	`print("Enter the value of the root node: ", end="")`
`23`	`24`	`check = raw_input().strip().lower()`
`24`	`25`	`if check == 'n':`
`25`		`- return None`
	`26`	`+ return None`
`26`	`27`	`data = int(check)`
`27`	`28`	`q = queue.Queue()`
`28`	`29`	`tree_node = TreeNode(data)`
`@@ -46,13 +47,15 @@ def build_tree():`
`46`	`47`	`node_found.right = right_node`
`47`	`48`	`q.put(right_node)`
`48`	`49`
	`50`	`+`
`49`	`51`	`def pre_order(node):`
`50`	`52`	`if not isinstance(node, TreeNode) or not node:`
`51`	`53`	`return`
`52`	`54`	`print(node.data, end=" ")`
`53`	`55`	`pre_order(node.left)`
`54`	`56`	`pre_order(node.right)`
`55`	`57`
	`58`	`+`
`56`	`59`	`def in_order(node):`
`57`	`60`	`if not isinstance(node, TreeNode) or not node:`
`58`	`61`	`return`
`@@ -82,22 +85,43 @@ def level_order(node):`
`82`	`85`	`if node_dequeued.right:`
`83`	`86`	`q.put(node_dequeued.right)`
`84`	`87`
`85`		`-#iteration version`
	`88`	`+`
	`89`	`+def level_order_actual(node):`
	`90`	`+ if not isinstance(node, TreeNode) or not node:`
	`91`	`+ return`
	`92`	`+ q = queue.Queue()`
	`93`	`+ q.put(node)`
	`94`	`+ while not q.empty():`
	`95`	`+ list = []`
	`96`	`+ while not q.empty():`
	`97`	`+ node_dequeued = q.get()`
	`98`	`+ print(node_dequeued.data, end=" ")`
	`99`	`+ if node_dequeued.left:`
	`100`	`+ list.append(node_dequeued.left)`
	`101`	`+ if node_dequeued.right:`
	`102`	`+ list.append(node_dequeued.right)`
	`103`	`+ print()`
	`104`	`+ for node in list:`
	`105`	`+ q.put(node)`
	`106`	`+`
	`107`	`+`
	`108`	`+# iteration version`
`86`	`109`	`def pre_order_iter(node):`
`87`	`110`	`if not isinstance(node, TreeNode) or not node:`
`88`	`111`	`return`
`89`	`112`	`stack = []`
`90`	`113`	`n = node`
`91`	`114`	`while n or stack:`
`92`		`- while n: #start from root node, find its left child`
	`115`	`+ while n: # start from root node, find its left child`
`93`	`116`	`print(n.data, end=" ")`
`94`	`117`	`stack.append(n)`
`95`	`118`	`n = n.left`
`96`		`- #end of while means current node doesn't have left child`
	`119`	`+ #end of while means current node doesn't have left child`
`97`	`120`	`n = stack.pop()`
`98`		`- #start to traverse its right child`
	`121`	`+ #start to traverse its right child`
`99`	`122`	`n = n.right`
`100`	`123`
	`124`	`+`
`101`	`125`	`def in_order_iter(node):`
`102`	`126`	`if not isinstance(node, TreeNode) or not node:`
`103`	`127`	`return`
`@@ -111,22 +135,24 @@ def in_order_iter(node):`
`111`	`135`	`print(n.data, end=" ")`
`112`	`136`	`n = n.right`
`113`	`137`
	`138`	`+`
`114`	`139`	`def post_order_iter(node):`
`115`	`140`	`if not isinstance(node, TreeNode) or not node:`
`116`	`141`	`return`
`117`	`142`	`stack1, stack2 = [], []`
`118`	`143`	`n = node`
`119`	`144`	`stack1.append(n)`
`120`		`- while stack1: #to find the reversed order of post order, store it in stack2`
	`145`	`+ while stack1: # to find the reversed order of post order, store it in stack2`
`121`	`146`	`n = stack1.pop()`
`122`	`147`	`if n.left:`
`123`	`148`	`stack1.append(n.left)`
`124`	`149`	`if n.right:`
`125`	`150`	`stack1.append(n.right)`
`126`	`151`	`stack2.append(n)`
`127`		`- while stack2: #pop up from stack2 will be the post order`
	`152`	`+ while stack2: # pop up from stack2 will be the post order`
`128`	`153`	`print(stack2.pop().data, end=" ")`
`129`	`154`
	`155`	`+`
`130`	`156`	`if __name__ == '__main__':`
`131`	`157`	`print("\n******* Binary Tree Traversals **********\n")`
`132`	`158`
`@@ -147,6 +173,10 @@ def post_order_iter(node):`
`147`	`173`	`level_order(node)`
`148`	`174`	`print("\n******************************************\n")`
`149`	`175`
	`176`	`+ print("\n******* Actual Level Order Traversal **********")`
	`177`	`+ level_order_actual(node)`
	`178`	`+ print("\n******************************************\n")`
	`179`	`+`
`150`	`180`	`print("\n******* Pre Order Traversal - Iteration Version **********")`
`151`	`181`	`pre_order_iter(node)`
`152`	`182`	`print("\n******************************************\n")`
`@@ -157,4 +187,4 @@ def post_order_iter(node):`
`157`	`187`
`158`	`188`	`print("\n******* Post Order Traversal - Iteration Version **********")`
`159`	`189`	`post_order_iter(node)`
`160`		`- print("\n******************************************\n")`
	`190`	`+ print("\n******************************************\n")`

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`‎traversals/binary_tree_traversals.py`

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