In the following two implementations for calculating
fibonacci sequence, fibonacci uses regular recursion and fibonacci_mem uses
memoization. fibonacci_mem is much more efficient as the value for any particular n is computed only once. When executed, the fibonacci function computes the value of some of the numbers in the sequence many times over, whereas fibonacci_mem reuses the value of n which was computed previously: The difference in performance may appear minimal with an n value of 5; however, as n increases, the
computational complexity of the original fibonacci function grows exponentially. In contrast, the fibonacci_mem version exhibits a more linear increase in complexity. ==See also==