From f39e1b99a5dc050e1f60f14257af0a320466a84b Mon Sep 17 00:00:00 2001
From: Shashank Kumar Srivastava
 <95871637+shashank0412@users.noreply.github.com>
Date: Fri, 6 Oct 2023 01:27:10 +0530
Subject: [PATCH] Create tree.cpp

---
 tree.cpp | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 tree.cpp

diff --git a/tree.cpp b/tree.cpp
new file mode 100644
index 0000000..c416166
--- /dev/null
+++ b/tree.cpp
@@ -0,0 +1,74 @@
+
+#include <bits/stdc++.h>
+
+void markParents(BinaryTreeNode<int> *root, unordered_map<BinaryTreeNode<int> *, BinaryTreeNode<int> *> &parent_track, BinaryTreeNode<int> *target)
+{
+    queue<BinaryTreeNode<int> *> queue;
+    queue.push(root);
+    while (!queue.empty())
+    {
+        BinaryTreeNode<int> *current = queue.front();
+        queue.pop();
+        if (current->left)
+        {
+            parent_track[current->left] = current;
+            queue.push(current->left);
+        }
+        if (current->right)
+        {
+            parent_track[current->right] = current;
+            queue.push(current->right);
+        }
+    }
+}
+
+vector<BinaryTreeNode<int> *> printNodesAtDistanceK(BinaryTreeNode<int> *root, BinaryTreeNode<int> *target, int k)
+{
+    unordered_map<BinaryTreeNode<int> *, BinaryTreeNode<int> *> parent_track;
+
+    markParents(root, parent_track, target);
+
+    unordered_map<BinaryTreeNode<int> *, bool> visited;
+
+    queue<BinaryTreeNode<int> *> queue;
+    queue.push(target);
+    visited[target] = true;
+    int curr_level = 0;
+
+    while (!queue.empty())
+    {
+        int size = queue.size();
+
+        if (curr_level++ == k)
+            break;
+
+        for (int i = 0; i < size; i++)
+        {
+            BinaryTreeNode<int> *current = queue.front();
+            queue.pop();
+            if (current->left && !visited[current->left])
+            {
+                queue.push(current->left);
+                visited[current->left] = true;
+            }
+            if (current->right && !visited[current->right])
+            {
+                queue.push(current->right);
+                visited[current->right] = true;
+            }
+            if (parent_track[current] && !visited[parent_track[current]])
+            {
+                queue.push(parent_track[current]);
+                visited[parent_track[current]] = true;
+            }
+        }
+    }
+    vector<BinaryTreeNode<int> *> result;
+    while (!queue.empty())
+    {
+        BinaryTreeNode<int> *current = queue.front();
+        queue.pop();
+        result.push_back(current);
+    }
+    return result;
+}