Search⌘ K
AI Features
Home
Courses
Recursion for Coding Interviews in JavaScript

Solution Review: Corresponding Fibonacci Number

Explore how to solve Fibonacci numbers using both iterative and recursive approaches. Understand the base cases, binary recursion, and how recursion differs from iteration, with clear JavaScript explanations.

We'll cover the following...

Solution #1: Iterative Method

Javascript (babel-node)
function fibonacci(testVariable) {
  var fn0 = 0;
  var fn1 = 1;
    
  for (let i = 0; i < testVariable; i++) {
    var temp = fn0 + fn1;
    // Setting variables for next iteration
    fn0 = fn1;
    fn1 = temp;
  }
  return fn0;
}
// Driver Code
var testVariable = 7;
console.log(fibonacci(testVariable));

Explanation

In the iterative method, we keep track of the two previous elements using the variables fn0 and fn1. Initially, the values of the two variables are:

fn0 = 0;
fn1 = 1;

However, in each iteration, the values are updated in the following way:

Solution #2: Recursive Method

Javascript (babel-node)
function fibonacci(testVariable) {
  // Base case
  if (testVariable <= 1) {
    return testVariable;
  }
  // Recursive case
  return(fibonacci(testVariable - 1) + fibonacci(testVariable - 2));
}
// Driver Code
var testVariable = 7;
console.log(fibonacci(testVariable));

Explanation:

In the code above, the function fibonacci() is a recursive function as it calls itself in the function body.

The base case of the function (line number 3) deals with the two initial values, i.e, for index 00 the value is ...