像C＃中的memoization Python？

Question

有沒有在C＃中類似的方式來做到以下幾點：

class Memoize: 
    def __init__(self, f): 
     self.f = f 
     self.memo = {} 
    def __call__(self, *args): 
     if not args in self.memo: 
      self.memo[args] = self.f(*args) 
     return self.memo[args] 

@Memoize 
def fib(n): 
    if n < 2: 
     return n 
    else: 
     return fib(n-1) + fib(n-2) 

Answer 1

你可以用手動做一個Dictionnary<int, int>：

public static int Fibonacci(int x) 
{ 
    var t = new Dictionary<int, int>(); 
    Func<int, int> fibCached = null; 
    fibCached = n => 
    { 
     if (t.ContainsKey(n)) return t[n]; 
     if (n <= 2) return 1; 
     var result = fibCached(n – 2) + fibCached(n – 1); 
     t.Add(n, result); 
     return result; 
    }; 
    return fibCached(x); 
}