Adding top_view_of_binary_tree.py

Author: yashdkadam

data_structures/binary_tree/top_view_of_binary_tree.py

@@ -0,0 +1,70 @@
+from collections import deque
+
+# Definition for a binary tree node
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.data = val
+        self.left = left
+        self.right = right
+
+class Solution:
+    # Function to return the top view of the binary tree
+    def topView(self, root):
+        # List to store the result
+        ans = []
+        
+        # Check if the tree is empty
+        if root is None:
+            return ans
+        
+        # Dictionary to store the top view nodes based on their vertical positions
+        mpp = {}
+        
+        # Queue for BFS traversal, each element is a pair containing node and its vertical position
+        q = deque([(root, 0)])
+        
+        # BFS traversal
+        while q:
+            # Retrieve the node and its vertical position from the front of the queue
+            node, line = q.popleft()
+            
+            # If the vertical position is not already in the map, add the node's data to the map
+            if line not in mpp:
+                mpp[line] = node.data
+            
+            # Process left child
+            if node.left:
+                # Push the left child with a decreased vertical position into the queue
+                q.append((node.left, line - 1))
+            
+            # Process right child
+            if node.right:
+                # Push the right child with an increased vertical position into the queue
+                q.append((node.right, line + 1))
+        
+        # Transfer values from the map to the result list
+        for key in sorted(mpp.keys()):
+            ans.append(mpp[key])
+        
+        return ans
+
+# Creating a sample binary tree
+root = TreeNode(1)
+root.left = TreeNode(2)
+root.left.left = TreeNode(4)
+root.left.right = TreeNode(10)
+root.left.left.right = TreeNode(5)
+root.left.left.right.right = TreeNode(6)
+root.right = TreeNode(3)
+root.right.right = TreeNode(10)
+root.right.left = TreeNode(9)
+
+solution = Solution()
+
+# Get the top view traversal
+top_view = solution.topView(root)
+
+# Print the result
+print("Top View Traversal:")
+for node in top_view:
+    print(node, end=" ")