メモ化

In computing, memoization or memoisation is an optimization technique used primarily to speed up computer programs. It works by storing the results of expensive calls to pure functions, so that these results can be returned quickly should the same inputs occur again. It is a type of caching, normally implemented using a hash table, and a typical example of a space–time tradeoff, where the runtime of a program is reduced by increasing its memory usage. Memoization can be implemented in any programming language, though some languages have built-in support that make it easy for the programmer to