recursion

问题 Here's my code- $arr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-" def scan(f) begin if f.size == 6 exit end $arr.each_char do |y| t = f + y puts t scan(t) end end end I wish to print all permutations and lengths upto 6, I've tried this recursive approach. The output I get is - A AA AAA AAAA AAAAA However I seek something like this- A AA AB AC . . AZ AAA AAB . . AAZ . . upto 6 chars On commenting the recursive call I see that it prints AA AB AC . . Which is fine without

问题 I have the folllowing solution to a problem relating to multiplicative persistence. However, I need to wipe the counter after each function call. I have tried different return statements, counters and arrays. I don't seem to be able to clear the counter after each function call AND get the correct answer. It is adding all the answers from multiple function calls. function persistence(num, counter = 0) { if (num.toString().length != 1) { num = num.toString().split("").filter(Number).reduce((a,

问题 I wrote a method to calculate the maximum depth of a binary tree. I would like to write a tail recursive method. I thought of using lists, but I didn't find solutions This is my method that is not tail recursive: def depth: Int = { def iter(f: FormulaWff): Int = f match { case Var(_) => 0 case Not(e1) => 1 + iter(e1) case And(e1, e2) => 1 + Math.max(iter(e1), iter(e2)) case Or(e1, e2) => 1 + Math.max(iter(e1), iter(e2)) case Implies(e1, e2) => 1 + Math.max(iter(e1), iter(e2)) } iter(this) }

问题 i am having trouble understanding this example. I cant figure out what actually happens after a certain point. Here is the code, the result is supposed to be 4. I can see that it calls itself several times but how it actually comes to the result of 4 eludes me entirely. Any help would be greatly appreciated. #include <stdio.h> int recursion(int i) { return (i>1 ? i - recursion(i/2) : 3); } int main() { int number = 9; printf("The result is %d\n", recursion(number)); return 0; } edit: Thanks

问题 this recursion code is from the book of eloquent javascript function power(base, exponent) { if (exponent == 0) { return 1; } else { return base * power(base, exponent - 1); } } console.log(power(2, 3)); obviously the exponent is decreased until it reached 0, if it is not zero, it adds power call on the stack, if it is zero, I start to see the return value of 1 then 2 then 4 then 8. But how did base got multiplied by exponent, how did base see the exponent value? it's on else and on power

问题 I have written a function to determine the height of a display, given a width and a format. The function operates recursively, if it cannot find a match for the given width and format while trying out a row of height values. The function works, if it finds a match before going into the recursion, but after that it always returns none and not the matching value pair. I am very confused as to why that is. Am I missing some principle here? def getDisplayDimensions(width,FormatX,FormatY): Format

问题 i'm making my own bbcode parser, and i've a problem when i try to do the recursive quote. this is my code : function forumBBCode($str){ $format_search=array( '#\[quote=(.*?)\](.*?)\[/quote\]#is' ); $format_replace=array( '<blockquote class="quotearea"><i><a class="lblackbu" href="./index.php?status=userview&userv=$1">$1</a> wrote :</i><br />$2</blockquote>' ); $str=preg_replace($format_search, $format_replace, $str); $str=nl2br($str); return $str; } what i must add/edit to do a recursive

问题 private void mergesort(int low, int high) { //line 1 if (low < high) { //line 2 int middle = (low + high)/2 ; //line 3 mergesort(low, middle); //line 4 mergesort(middle+1, high); //line 5 merge(low, middle, high); //line 6 }} //line 7 I understand the fact that when the if statement is false you exit the method/function. For example, if i call mergesort(0, 5) in the main method the first mergesort(low, middle) will run 3 times and terminate, then the program will go to line 7. What i am

问题 I was trying to make recursive function that would simulate two for loops. So, function would have to do this: int recursion(int n, int i, int j) { for(i=0; i<n; i++) { for(j=i+1; j<n; j++) { printf("%d %d\n", i, j); } } } but, i want it to be recursive. I tried something like: int recursion(int n, int i, int j) { if(i<n) { if(j<n) { printf("%d %d\n", i, j); recursion(n, i+1, j+1); } recursion(n, i+1, i+1+1); } } I would call recursive one in main like recursion(10, 0, 1); but output is not

问题 I'm having a problem finishing off my script, it works using map.setCenter to reposition on each marker, but I would like to pan to each new marker. However, when I use the panTo function the markers don't appear, although the map does show and pans around to where each new marker would be. Firebug gives me a "too much recursion" error too. Can anyone help? <script type="text/javascript"> var map = {}; var mapOptions; var infowindow; var marker; var lat, lng; var latlng; var gender; var