recursion

问题 This code does NOT work: def inc(x): return x + 1 def repeat(f, n): if n == 0: return lambda x: x else: return f( repeat(f, n - 1 ) ) inc_10 = repeat(inc, 10) #TypeError: unsupported operand type(s) for +: 'function' and 'int' ''' # Ideally print(inc_10(0)) # 10 ''' How can I write it in a more Pythonic way or in lambda calculus way ? 回答1: You still need to return a function, not the result of calling f , in the recursive case. # repeat :: (a -> a) -> Integer -> a -> a # repeat _ 0 = id #

问题 My application references a database object that acts as a catalog. It's a catalog of items that can be crafted if the user has the necessary components. Here is a small sample of the catalog: const itemCatalog = { "bramble_vest" : { "components" : [ "Chain Vest", "Chain Vest" ], "name" : "Bramble Vest" }, "guardian_angel" : { "components" : [ "B.F. Sword", "Chain Vest" ], "name" : "Guardian Angel" }, "hextech_gunblade" : { "components" : [ "B.F. Sword", "Needlessly Large Rod" ], "name" :

问题 I am stuck since 2 days, as I am not to firm with pointers and recursion. I have an array of path like structures, lets say: s:=[]string { "a/b/c", "a/b/g", "a/d", } With a data structure like this: type Node struct { Name string `json:"name"` Children []Node `json:"children"` } I would like to end up with something like this: { "name": "a", "children": [ { "name": "b", "children": [ { "name": "c", "children": [] }, { "name": "g", "children": [] } ] }, { "name": "d", "children": [] } ] } I

问题 I've two functions fun() and fun2(); fun() calls itself while incrementing the global variable a=0 and terminates if a==5. But if I call another function called fun2() which basically returns and do nothing, then Build Error happens. Why? I'm just experimenting with recursion and I got this error. #include<iostream> using namespace std; int a = 0; void fun() { if (a == 5) return; a++; fun(); fun2(); //This is where the trouble happens } void fun2() { return; } int main() { fun(); return 0; }

问题 I've two functions fun() and fun2(); fun() calls itself while incrementing the global variable a=0 and terminates if a==5. But if I call another function called fun2() which basically returns and do nothing, then Build Error happens. Why? I'm just experimenting with recursion and I got this error. #include<iostream> using namespace std; int a = 0; void fun() { if (a == 5) return; a++; fun(); fun2(); //This is where the trouble happens } void fun2() { return; } int main() { fun(); return 0; }

问题 Background I want to show part of my bookmarks on my Hugo website. The bookmarks from Firefox can be saved in JSON format, this is the source. The result should represent the nested structure somehow, in a format of a nested list, treeview or accordion. The source files of contents on the website are written in markdown. I want to generate a markdown file from the JSON input. As I searched for possible solutions: treeview or accordion: HTML, CSS and Javascript needed. I could not nest

问题 I get a stack overflow error due to my recursion creating an infinite loop. Turning the method into an iteration would stop this, but I have no idea how! Can anyone guide me in turning my recursion into a loop? private int findEmpty(int startPos, int stepNum, String key) { if (arr[startPos] == null) { return startPos; } return findEmpty(getNextLocation(startPos, ++stepNum, key), stepNum, key); } It is specifically return findEmpty(getNextLocation(startPos, ++stepNum, key), stepNum, key); that

问题 I get a stack overflow error due to my recursion creating an infinite loop. Turning the method into an iteration would stop this, but I have no idea how! Can anyone guide me in turning my recursion into a loop? private int findEmpty(int startPos, int stepNum, String key) { if (arr[startPos] == null) { return startPos; } return findEmpty(getNextLocation(startPos, ++stepNum, key), stepNum, key); } It is specifically return findEmpty(getNextLocation(startPos, ++stepNum, key), stepNum, key); that

问题 I have a Node class defined as follows. value: T is a String class Node<T> { var value: T weak var parent: Node? var children = [Node<T>]() init(_ value: T) { self.value = value } func add(_ node: Node<T>) { children.append(node) node.parent = self } } I'd like to build a function to return a String of the current Node's value and all Parent values. Ideally, the function would be defined in the class. For example, currentnode.listAllValues() would return -> "/parent2value/parent1value

问题 I have a Node class defined as follows. value: T is a String class Node<T> { var value: T weak var parent: Node? var children = [Node<T>]() init(_ value: T) { self.value = value } func add(_ node: Node<T>) { children.append(node) node.parent = self } } I'd like to build a function to return a String of the current Node's value and all Parent values. Ideally, the function would be defined in the class. For example, currentnode.listAllValues() would return -> "/parent2value/parent1value