Below function returns out the n-th entry in the fibonacci series.

private fun fibonacciSequenceRecursiveCached(n: Int): Int {
    if (n < 2) {
        return n
    }

    return fibonacciSequenceRecursiveCached(n - 1) + fibonacciSequenceRecursiveCached(n - 2)
}

However due to recursion this function has exponential complexity (function is called recursively multiple times with identical arguments), so its execution takes a long time. Store arguments of each call along with the result using MethodCache class.

private data class MethodCache(val n: Int, val result: Int)

If the function is called again with the same arguments, return the precomputed result rather than running the function again.

Challenge | Solution