Fibonacci Using Recursion in DSA Typescript - Build from Scratch

Fibonacci Using Recursion

📖 Scenario: You want to calculate the Fibonacci number at a certain position. The Fibonacci sequence starts with 0 and 1, and each next number is the sum of the two before it.Imagine you are building a simple calculator that finds the Fibonacci number for a given position using a method called recursion, where the function calls itself.

🎯 Goal: Build a recursive function called fibonacci that takes a number n and returns the Fibonacci number at position n.Then, use this function to find the Fibonacci number at position 6 and print the result.

📋 What You'll Learn

Create a variable n with the value 6.

Create a recursive function called fibonacci that takes a number num and returns the Fibonacci number at that position.

Use the base cases: if num is 0, return 0; if num is 1, return 1.

For other cases, return the sum of fibonacci(num - 1) and fibonacci(num - 2).

Call the fibonacci function with n and store the result in a variable called result.

Print the value of result.

💡 Why This Matters

🌍 Real World

Fibonacci numbers appear in nature, computer algorithms, and financial models. Understanding recursion helps solve problems that break down into smaller similar problems.

💼 Career

Recursion is a key concept in programming interviews and algorithm design. Knowing how to write and understand recursive functions is important for software development roles.

1

Create the input variable

Create a variable called n and set it to the number 6.

DSA Typescript

# Your code here

Hint

Use const n = 6; to create the variable.

2

Write the recursive Fibonacci function

Create a function called fibonacci that takes a parameter num of type number. Inside the function, write these rules:
- If num is 0, return 0.
- If num is 1, return 1.
- Otherwise, return fibonacci(num - 1) + fibonacci(num - 2).

DSA Typescript

const n = 6;
// Your code here

Hint

Use function fibonacci(num: number): number { ... } and the base cases with if statements.

3

Call the function and store the result

Call the fibonacci function with the variable n and store the returned value in a variable called result.

DSA Typescript

const n = 6;

function fibonacci(num: number): number {
    if (num === 0) {
        return 0;
    }
    if (num === 1) {
        return 1;
    }
    return fibonacci(num - 1) + fibonacci(num - 2);
}

// Your code here

Hint

Use const result = fibonacci(n); to call the function and save the answer.

4

Print the Fibonacci result

Print the value of the variable result using console.log.

DSA Typescript

const n = 6;

function fibonacci(num: number): number {
    if (num === 0) {
        return 0;
    }
    if (num === 1) {
        return 1;
    }
    return fibonacci(num - 1) + fibonacci(num - 2);
}

const result = fibonacci(n);

// Your code here

Hint

Use console.log(result); to show the answer.