adding new algo

Author: ivanpenaloza

src/my_project/interviews/top_amazon_questions_round_1/all_nodes_distance_k_in_binary_tree.py

@@ -0,0 +1,36 @@
+from typing import List 
+
+class TreeNode:
+    def __init__(self, x):
+        self.val = x
+        self.left = None
+        self.right = None
+
+class Solution:
+    def distanceK(self, root: TreeNode, target: TreeNode, k: int) -> List[int]:
+        def helper(node, parent):
+            if not node:
+                return
+            node.parent = parent
+            helper(node.left, node)
+            helper(node.right, node)
+            
+        helper(root, None)
+        ans = []
+        seen = set()
+        
+        def trav(node, dist):
+            if not node or node in seen or dist > k:
+                return
+            seen.add(node)
+            if dist == k:
+                ans.append(node.val)
+                return
+            if dist+1 <= k:
+                trav(node.parent, dist+1)
+                trav(node.left, dist+1)
+                trav(node.right, dist+1)
+        
+        trav(target, 0)
+        return ans
+