memoization

问题 I've not seen (yet?) JSON.stringify to be non-deterministic in Node.JS. There is no guarantee it to be deterministic on the specification level. But what about V8; Is its implementation there deterministic? Is there a guarantee for it to remain deterministic for future V8 versions? Edit: With deterministic I mean that following assertion is true no matter what the value of json_str is. (Given the value is a valid JSON string.) const obj = JSON.parse(json_str); assert(JSON.stringify(obj)==

问题 I've not seen (yet?) JSON.stringify to be non-deterministic in Node.JS. There is no guarantee it to be deterministic on the specification level. But what about V8; Is its implementation there deterministic? Is there a guarantee for it to remain deterministic for future V8 versions? Edit: With deterministic I mean that following assertion is true no matter what the value of json_str is. (Given the value is a valid JSON string.) const obj = JSON.parse(json_str); assert(JSON.stringify(obj)==

来源： https://stackoverflow.com/questions/19055840/finding-out-the-maximum-number-if-cost-is-associated-with-using-each-digit

来源： https://stackoverflow.com/questions/19055840/finding-out-the-maximum-number-if-cost-is-associated-with-using-each-digit

来源： https://stackoverflow.com/questions/19055840/finding-out-the-maximum-number-if-cost-is-associated-with-using-each-digit

来源： https://stackoverflow.com/questions/19055840/finding-out-the-maximum-number-if-cost-is-associated-with-using-each-digit

来源： https://stackoverflow.com/questions/6469437/what-is-the-difference-between-caching-and-memoization

问题 Here's a little piece of code which converts every function to its memoization version. def memoize(f): # Memoize a given function f def memf(*x): if x not in memf.cache: memf.cache[x] = f(*x) return memf.cache[x] memf.cache = {} return memf For instance, if we have a function fib as follows which returns the n th Fibonacci number: def fib(n): if n < 2: return 1 else: return fib(n-1) + fib(n-2) Now, the above function can be memoized by using fib = memoize(fib) Everything is fine up to this

问题 Any pointers on how to solve efficiently the following function in Haskell, for large numbers (n > 108) f(n) = max(n, f(n/2) + f(n/3) + f(n/4)) I've seen examples of memoization in Haskell to solve fibonacci numbers, which involved computing (lazily) all the fibonacci numbers up to the required n. But in this case, for a given n, we only need to compute very few intermediate results. Thanks 回答1: We can do this very efficiently by making a structure that we can index in sub-linear time. But

问题 Any pointers on how to solve efficiently the following function in Haskell, for large numbers (n > 108) f(n) = max(n, f(n/2) + f(n/3) + f(n/4)) I've seen examples of memoization in Haskell to solve fibonacci numbers, which involved computing (lazily) all the fibonacci numbers up to the required n. But in this case, for a given n, we only need to compute very few intermediate results. Thanks 回答1: We can do this very efficiently by making a structure that we can index in sub-linear time. But