<p>Given the <code>root</code> of a binary tree, the value of a target node <code>target</code>, and an integer <code>k</code>, return <em>an array of the values of all nodes that have a distance </em><code>k</code><em> from the target node.</em></p>

<p>You can return the answer in <strong>any order</strong>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/06/28/sketch0.png" style="width: 500px; height: 429px;" />
<pre>
<strong>Input:</strong> root = [3,5,1,6,2,0,8,null,null,7,4], target = 5, k = 2
<strong>Output:</strong> [7,4,1]
Explanation: The nodes that are a distance 2 from the target node (with value 5) have values 7, 4, and 1.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> root = [1], target = 1, k = 3
<strong>Output:</strong> []
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 500]</code>.</li>
	<li><code>0 &lt;= Node.val &lt;= 500</code></li>
	<li>All the values <code>Node.val</code> are <strong>unique</strong>.</li>
	<li><code>target</code> is the value of one of the nodes in the tree.</li>
	<li><code>0 &lt;= k &lt;= 1000</code></li>
</ul>

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
map<TreeNode*,TreeNode*>mp;

 void parent_s(TreeNode*root)
 {
   if(root->left!=NULL) 
   {
        mp[root->left]=root;
       // cout<<root->left->val<<" "<<" setted "<<endl;
        parent_s(root->left);
   }
   if(root->right!=NULL)
   {
    mp[root->right]=root;
    parent_s(root->right);
   } 


 }
    vector<int> distanceK(TreeNode* root, TreeNode* target, int k)
    {

        parent_s(root);
        vector<int>vt;
        mp[root]=NULL;
        queue<pair<int,TreeNode*>>qu;
        qu.push({0,target});
        while(!qu.empty())
        {
            auto it=qu.front();
            qu.pop();
             // cout<<"reached"<<it.second->val<<endl;
            if(it.first==k)
            {
                vt.push_back(it.second->val);

            }
            
            if(it.second->left!=NULL)
            {
                qu.push({it.first+1,it.second->left});
                mp[it.second->left]=NULL;

            }

            if(it.second->right!=NULL)
            {
                qu.push({it.first+1,it.second->right});
                mp[it.second->right]=NULL;

            }
            
            if(mp[it.second]!=NULL)
            {
                qu.push({it.first+1,mp[it.second]});

                if(mp[it.second]->left==it.second)mp[it.second]->left=NULL;
                else
                mp[it.second]->right=NULL;
                

            }


        }
return vt;
    }
};
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