The ultimate guide to recursion interviews with strategies developed by FAANG engineers. Practice with real-world interview questions, detailed explanations, and visualizations to prep faster.

If you’ve got an interview coming up and want to brush up on your knowledge, or if you’ve ever struggled with solving coding problems using recursion, you'll find this course helpful.
 
You’ll start with the basics of what recursion is and why it’s important before diving into what it looks like in practice. You’ll see how recursion can help you solve a variety of different math, string, and data structure problems by using interactive code playgrounds that you can execute directly in your browser. You’ll have access to detailed explanations and visualizations for each problem to help you along the way.  
 
By the time you’re done, you’ll be able to use what you’ve learned to solve complex real-world problems and even advance more easily through your interviews at top tech companies.

Recursion for Coding Interviews in Java

 ```Java
 if (head == null)
    {
        return;
    }
```

 ```Java
 if (head.next == null)
    {
        return;
    }
```

Imagine you have a linked list with five nodes. Your task is to traverse the linked list recursively.  
``` Java
public static void printListRecursively (Node head)
{
    //base case
    //recursive case
    System.out.print(head.data + " ");
    printListRecursively(head.next);
}
````
What is the base case of the above code?

Imagine you have a linked list with five nodes. Your task is to traverse the linked list recursively.
<pre><code class="language-Java">public static void printListRecursively (Node head)
{
 //base case
 //recursive case
 System.out.print(head.data + &quot; &quot;);
 printListRecursively(head.next);
}
</code></pre>
What is the base case of the above code?

``` Java
if ( visited[v] == 0 ) { return; }
```

``` Java
if ( visited[v] == 1 ) { return;}
```

Imagine you have a graph with four nodes. 
The graph has the following edges as follows: 
{ [ 0,1 ], [ 0,2 ] ,[ 1,4 ], [ 1,3 ], [ 2, 4 ] } 
The function below prints the nodes and vertices connected to each vertex . 

``` Java
public static void connected (int v, vector<int>visited)
{
 //base case
 //recursive case
 	connected(v+1,visited);
 
 
}
````
What is the base case of the above code?

Imagine you have a graph with four nodes.
The graph has the following edges as follows:
{ [ 0,1 ], [ 0,2 ] ,[ 1,4 ], [ 1,3 ], [ 2, 4 ] }
The function below prints the nodes and vertices connected to each vertex .
<pre><code class="language-Java">public static void connected (int v, vector&lt;int&gt;visited)
{
 //base case
 //recursive case
 	connected(v+1,visited);
 
 
}
</code></pre>
What is the base case of the above code?

``` Java
if (root != NULL)
 
  {
    root = newTreeNode(data);
    return;
  }
```

```Java
if (root == null) 
  {
    root = newTreeNode(data);
    return;
  }
```

```Java
if (root == null) 
  {
    return;
  	root = newTreeNode(data);
  }
```

See the code for BST implementation below:

```Java
public class TreeNode
{
 int value;
 TreeNode left; 
 TreeNode right;


 public static TreeNode newTreeNode(int data)
 {
 TreeNode temp = new TreeNode();
 temp.value = data;
 temp.left = null;
 temp.right = null;

 return temp;
 }

 void insert(TreeNode root, int data)
 {
 if (data < root.value)
 {
 insert(root.left,data); 
 }
 else
 {	
 insert(root.right, data); 
 }
 } 
}

```
What is the base case for the `insert` function?

See the code for BST implementation below:
<pre><code class="language-Java">public class TreeNode
{
 int value;
 TreeNode left; 
 TreeNode right;


 public static TreeNode newTreeNode(int data)
 {
 TreeNode temp = new TreeNode();
 temp.value = data;
 temp.left = null;
 temp.right = null;

 return temp;
 }

 void insert(TreeNode root, int data)
 {
 if (data &lt; root.value)
 {
 insert(root.left,data); 
 }
 else
 {	
 insert(root.right, data); 
 }
 } 
}

</code></pre>
What is the base case for the <code>insert</code> function?

Solve this Quiz!

Solve this Quiz!

This lesson will test your knowledge on how to solve the linked list, tree, and graph problems using recursion.

Fundamentals of Recursion

Iteration to Recursion

Recursion with Numbers

Recursion with Strings

Recursion with Arrays

Recursion with Data Structures

Quick Quiz on Recursion with Data Structures!