Print Nodes in Bottom View of Binary Tree

Author: anubhavshrimal

README.md

@@ -158,6 +158,7 @@ Contains implementation of Tree data structure and some common questions and alg
 
 | 			Topic/Question			|	Code File Name |
 |-----------------------------------|------------------|
+|Print Nodes in Bottom View of Binary Tree|Bottom_View.py|
 |Check if a binary tree is height balanced|Check_Balanced.py|
 |Given two binary trees, check if the first tree is subtree of the second one|Is_SubTree.py|
 |Find the Lowest Common Ancestor in a Binary Tree|Lowest_Common_Ancestor.py|

Tree/BinaryTree/Bottom_View.py

@@ -0,0 +1,56 @@
+# Print Nodes in Bottom View of Binary Tree
+from collections import deque
+
+
+class Node:
+    def __init__(self, data):
+        self.data = data
+        self.left = None
+        self.right = None
+
+
+def bottom_view(root):
+    if root is None:
+        return
+
+    # make an empty queue for BFS
+    q = deque()
+
+    # dict to store bottom view keys
+    bottomview = {}
+
+    # append root in the queue with horizontal distance as 0
+    q.append((root, 0))
+
+    while q:
+        # get the element and horizontal distance
+        elem, hd = q.popleft()
+
+        # update the last seen hd element
+        bottomview[hd] = elem.data
+
+        # add left and right child in the queue with hd - 1 and hd + 1
+        if elem.left is not None:
+            q.append((elem.left, hd - 1))
+        if elem.right is not None:
+            q.append((elem.right, hd + 1))
+
+    # return the bottomview
+    return bottomview
+
+
+if __name__ == '__main__':
+    root = Node(20)
+    root.left = Node(8)
+    root.right = Node(22)
+    root.left.left = Node(5)
+    root.left.right = Node(3)
+    root.right.left = Node(4)
+    root.right.right = Node(25)
+    root.left.right.left = Node(10)
+    root.left.right.right = Node(14)
+
+    bottomview = bottom_view(root)
+    
+    for i in sorted(bottomview):
+        print(bottomview[i], end=' ')