Fibonacci

// solution 1
function fibonacci(n){
  if(n < 2){
    return n;
  }

  // temporary variables
  let prev = 0;
  let curr = 1;
  let arr = [0, 1];

  for(let i = 2; i <= n; i++){
    // add prev value to curr
    const sum = prev + curr;
    arr.push(sum)
    console.log(prev, curr, sum)
    
    // switch prev and curr values
    prev = curr;
    curr = sum;
  }
  console.log(arr)
  return curr
}

// solution 2
// Improvement after googling
function fibonacci2(n){
  if(n < 2){
    return n;
  }

  let arr = [0, 1];

  for(let i = 2; i <= n; i++){
    // save solutions
    arr[i] = arr[i-1] + arr[i-2];
    console.log(arr)
  }
  return arr[n]
}

fibonacci2(6)