recursion

问题 I have only Nth number of level array return, this function return all children list $arr = array( array('id'=>100, 'parentid'=>0, 'name'=>'a'), array('id'=>101, 'parentid'=>100, 'name'=>'a'), array('id'=>102, 'parentid'=>101, 'name'=>'a'), array('id'=>103, 'parentid'=>101, 'name'=>'a'), ); $new = array(); foreach ($arr as $a){ $new[$a['parentid']][] = $a; } $tree = createTree($new, array($arr[0])); print_r($tree); function createTree(&$list, $parent){ $tree = array(); foreach ($parent as $k=

问题 This question already has answers here : How does this recursion work? (11 answers) Closed 26 days ago . I'm going through eloquent javascript & this recursive function has me stumped, I understand most of it. function findSolution(target) { function find(current, history) { if (current == target) { return history; } else if (current > target) { return null; } else { return find(current + 5, `(${history} + 5)`) || find(current * 3, `(${history} * 3)`); } } return find(1, "1"); } console.log

问题 I am working on recursive function that fills a list. I encountered a problem that when I try to return the list itself I recieve None argument. However, if I print the same argument I got the correct list back. Any idea why I see such behavour? Example: def Price(tau, price): price[tau] = (tau**2 - tau) + price[tau+1] - price[tau+2] if tau == 0: return price else: tau = tau - 1 Price(tau, price) print(Price(tau = 3, price = 6*[0])) > None However just prining the price , gives correct result

问题 Hi I have looked up a few recursive multiplication of 2 numbers in python, but none of them take into account the possibility of negative numbers or if they do they don't explain the entire steps. I have coded the following the program but I am getting an error, can someone please let me know what is wrong with it? def mult(a,b): if a==0 | b==0: return 0 elif a==1: return b elif a > 0 & b >0: return b + mult(a-1,b) elif a < 0 & b > 0: return - b + mult(a+1,b)) elif a > 0 & b < 0: return - b +

问题 I have this code, but there is an recursive function and i can't optimize it, that's why i always have StackOverFlow exception. Can you help me to optimize it? I use this void to get all info or to try again if some errors are found. public void Parse(byte[] data) { Socket skt = new Socket(SocketType.Dgram, ProtocolType.Udp); skt.ReceiveTimeout = 1000; skt.Connect(Encryptor.GetNextIP(), port); skt.Send(data); try { //a lot of actions to get the opcode switch (opCode) { case 0x01: p = new

问题 I have linked together groups of records which are related via a shared parent. Unfortunately there are some quite complicated family groups, and it's become clear that just using a shared parental relationship isn't enough - I also want to take into account sibling relationships. To be clear - this is actual family groups, which are currently identified if their is a shared mother or father relationship, but in some cases a child may not share parents with another child who is still linked

问题 I found this code on another SO post: fun number_in_month ([], _) = 0 | number_in_month ((_,x2,_) :: xs, m) = if x2 = m then 1 + number_in_month(xs, m) else number_in_month(xs, m) and to my surprise it works. - number_in_month ([(2018,1,1),(2018,2,2),(2018,2,3),(2018,3,4),(2018,2,30)],2); val it = 3 : int My confusion is first unfamiliarity with this form of classic mathematical recursive function (I'm a beginner), then how it actually steps through the list. My intuition would have the

问题 I'm trying to iterate depth-first over a tree structure in Rust. I thought I had a really nice concise solution for this, but I can't get it to compile. Conceptually it's pretty simple: iterate over the children, get each child's depth first iterator, flatten them, and chain the current node's metadata iterator to it. #[derive(Debug, Eq, PartialEq)] struct Node { metadata: Vec<i64>, children: Vec<Box<Node>>, } impl Node { fn depth_first_metadata_iter(&self) -> impl Iterator<Item = &i64> + '_

问题 Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 6 years ago . Improve this question Hi I want to write a code for a pow function without using math.h libary. How is this code?how can i fix it when b<0 int MyPow(int a,int b){ if(b<0) return 1 / MyPow (a,-b) else if(b==0) return 1; else if(b==1) return a; else return a*MyPow(a,b-1) } 回答1:

问题 I am a novice programmer I am looking up into a problem which is using a recursive function. Though I could understand the main point, there is an unclear issue which I could not decipher immediately as I go through the debugging process. I will appreciate your help on my question. The problem's concept ( merge sorting ) is pretty straight forward, but I am confused with the way a recursive function works in general. Bellow is the program I am dealing with (from Georgia Tech course on Python)