> For the complete documentation index, see [llms.txt](https://gl01.gitbook.io/gfg-editorials/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gl01.gitbook.io/gfg-editorials/2024/05-2024-may/03-k-distance-from-root.md).

# 03. K distance from root

The problem can be found at the following link: [Question Link](https://www.geeksforgeeks.org/problems/k-distance-from-root/1)

## My Approach

* If root is null, return.
* If k equals 0, push the data of the current root node into the ans vector and return.
* Recursively call traverse function for the left child of root with k-1.
* Recursively call traverse function for the right child of root with k-1.
* Clear the ans vector.
* Call traverse function with the root node and distance k.
* Return the ans vector containing nodes at distance k from the root.

## Time and Auxiliary Space Complexity

* **Time Complexity**: `O(N)`, where `N` is the number of nodes in the tree.
* **Auxiliary Space Complexity**: `O(H)`, where `H` is the height of the tree.

## Code (C++)

```cpp
class Solution
{
    public:
    // function should print the nodes at k distance from root
    vector<int> ans;

    void traverse(struct Node *root, int k)
    {
        if(!root)
            return;
        if(k == 0)
        {
            ans.push_back(root->data);
            return;
        }
        traverse(root->left, k-1);
        traverse(root->right, k-1);
    }

    vector<int> Kdistance(struct Node *root, int k) 
    {
        ans.clear();
        traverse(root, k);
        return ans;
    }
};
```

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