Merge pull request #176 from dsrao711/issue171

Python solution for Vertical order traversal

Author: smv1999

DSA 450 GFG/vertical_order_traversal.py

@@ -0,0 +1,25 @@
+#Link to the problem : https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/
+
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def verticalTraversal(self, root):
+      
+        def _traverse(node, row, col, cache):
+          
+            if not node:
+                return
+            _traverse(node.left, row + 1, col - 1, cache)
+            cache[col].append((row, node.val))
+            _traverse(node.right, row + 1, col + 1, cache)
+        
+        cache = defaultdict(list)
+        _traverse(root, 0, 0, cache)
+        ans = []
+        for key in sorted(cache):
+            ans.append(x[1] for x in sorted(cache[key]))
+        return ans