Recursion for Coding Interviews in Java/

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Understanding a Recursive Problem

Understanding a Recursive Problem

In this lesson, we will go deep into understanding a recursive problem.

We'll cover the following...

Understanding the Problem

You should now have a clear understanding of how recursion works - what it is and when it can be used. Before you proceed writing your own recursive code, it is very important to understand the nitty-gritty details of how the code actually works.

Below is a basic example of how the order of execution for a recursive method changes at each successive recursive call.

Example

What do you think is the output of the code below? Take your time to think it over before you execute the code and look at the result.

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class ExampleClass {
    private static void printNum(int n) {
        // Base case
        if (n == 0) {
            return;
        }
        // Recursive case
        printNum(n-1);
        System.out.print(n + " ");
    }
    public static void main( String args[] ) {
        // Recursive method called here
        printNum(6);   
    }
}

Code Explanation

If we read the method as it is written, we might expect the output to be 6,5,4,3,2,16, 5, ...