Memoisaatio

Memoisaatio is a Finnish term that translates to "memoization" in English. It refers to an optimization technique used primarily in computer programming to speed up function calls by storing the results of expensive function calls and returning the cached result when the same inputs occur again. Essentially, it's a way to avoid recomputing a value that has already been computed.

When a function with memoization is called, it first checks if it has already computed the result for the given input arguments. If a cached result exists, it is returned immediately. If not, the function proceeds with its computation, stores the result along with its input arguments, and then returns the newly computed result. This approach is particularly effective for functions that are computationally intensive and are likely to be called multiple times with the same parameters.

Memoization is a form of caching. It differs from simple caching in that it specifically applies to function return values. Common applications include dynamic programming, where subproblems are solved and their results stored to avoid redundant calculations. In recursive functions, memoization can significantly reduce the number of recursive calls, preventing exponential time complexity in many cases. The trade-off for the speed improvement is the use of additional memory to store the computed results.