recursion

问题 I am trying to get parent child relation and successfully get that But I am stuck how to identify what is the level of the child. Here is my code public function getDownline($userid = null) { $category_data = array(); $where = array('parent_id' => $userid); $this->db->where($where); $category_query = $this->db->get('users')->result(); $category_data = array(); foreach ($category_query as $category) { $category_data[$category->id] = array($category); $children = $this->getDownline($category-

问题 #include<stdio.h> void printd(int n) { if(n/10) printd(n/10); putchar(n%10+'0'); } In the above code consider n as a positive integer and its value be 123. First time,123 is passed to printd (first printd) Second time,12 is passed to printd (second printd) Third time,1 is passed to printd (third printd) and putchar prints 1 Then after the control flows to second printd,what is the value of n? Since it is an automatic variable it's value of 1 in third printd vanishes once the function ends and

问题 I have a database table which looks like this: ID | PredecessorID | Data -------------------------------------|--------------------------------------|----------------- 43b1e103-d8c6-40f9-b031-e5d9ef18a739 | null | ... 55f6951b-5ed3-46c8-9ad5-64e496cb521a | 43b1e103-d8c6-40f9-b031-e5d9ef18a739 | ... 3eaa0889-31a6-449d-a499-e4beb9e4cad1 | 55f6951b-5ed3-46c8-9ad5-64e496cb521a | ... I know that I can use a (recursive) common table expression (CTE) to get a sorted list of my data: WITH cte (ID,

问题 hey, I have this array (the actual array can be several level deeps and spans a tree-structure) array 3 => array 4 => array 7 => null 8 => null 5 => null 6 => null Now, e.g. I want the path to key 7 , it can be shown like this: array 0 => int 7 1 => int 4 2 => int 3 Can someone help me with such a recursion function? 回答1: This will return you what you are looking for. It will return null if the key is not found. In codepad. function getkeypath($arr, $lookup) { if (array_key_exists($lookup,

问题 I have the following recursive function in Scala that should return the maximum size integer in the List. Is anyone able to tell me why the largest value is not returned? def max(xs: List[Int]): Int = { var largest = xs.head println("largest: " + largest) if (!xs.tail.isEmpty) { var next = xs.tail.head println("next: " + next) largest = if (largest > next) largest else next var remaining = List[Int]() remaining = largest :: xs.tail.tail println("remaining: " + remaining) max(remaining) }

问题 I have a recursive scalar function that needs to update a record in another table based on the value it is returning, however UPDATE statements are not allowed in the function. How can I update the table from within the function? 回答1: UPDATE statements are not allowed in the function That's the rule - functions are not allowed to have any data-changing side-affects. You have to use a Stored Procedure to UPDATE . 来源： https://stackoverflow.com/questions/3805250/sql-server-how-to-execute-update

问题 I have to generate all the possible binary representations of a given string, where some characters are "?" and others are 1 or 0. I'm trying to do a recursive search but I encounter some weird problems I can't figure out. userInput = list(input()) anslist = [] def fill(inp): #print(inp) if inp.count("?") == 0: print(inp, "WAS ADDED") anslist.append(inp) return for a in range(0, len(userInput)): if inp[a] == "?": inp[a] = 1 fill(inp) inp[a] = 0 fill(inp) return print(anslist) For the input

问题 In Java, constructors cannot be recursive. Compile time error: "recursive constructor invocation". Let's assume that we did not have this restriction. Things to keep in mind: The return type of a constructor is void. Since it is a void method you can't harness the complete power of recursion. A constructor can invoke itself (or any other constructor) using this(). But a "call to this must be first statement in constructor" We could use non local data between consecutive calls to still have

问题 I need some help on the SimpleXML calls for a recursive function that lists the elements name and attributes. Making a XML config file system but each script will have it's own config file as well as a new naming convention. So what I need is an easy way to map out all the elements that have attributes, so like in example 1 I need a simple way to call all the processes but I don't know how to do this without hard coding the elements name is the function call. Is there a way to recursively

问题 In Java, constructors cannot be recursive. Compile time error: "recursive constructor invocation". Let's assume that we did not have this restriction. Things to keep in mind: The return type of a constructor is void. Since it is a void method you can't harness the complete power of recursion. A constructor can invoke itself (or any other constructor) using this(). But a "call to this must be first statement in constructor" We could use non local data between consecutive calls to still have