fibonacci with memoisation

factorial

// 5 * 4 * 3 * 2 * 1
const factorial = (n) => {
  //base case
  if (n === 1) return 1;
  // logic
  return n * factorial(n-1);
}


console.log(factorial(5))

fibonacci_memoised

const fib = (n, mem) => {
// memoise
mem = mem || {};
//base case
if (n <= 1) return 1;
if (mem[n]) return mem[n];
return mem[n] = fib(n-1, mem) + fib(n-2, mem);
}

console.log(fib(5)) // return 8