iteration

问题 If I run the following code, it will print out 3 times duplicate, but when I remove the if statement inside the while loop (just to see how many times it will iterate) it starts an infinite loop. How does actually this hasNext() method working? I thought that will iterate only 5 times as I have 5 items in the list. public class ExerciseOne { public static void main(String []args){ String []colors = {"MAGENTA","RED","WHITE","BLUE","CYAN"}; List<String> list = new ArrayList<String>(); for

问题 If I run the following code, it will print out 3 times duplicate, but when I remove the if statement inside the while loop (just to see how many times it will iterate) it starts an infinite loop. How does actually this hasNext() method working? I thought that will iterate only 5 times as I have 5 items in the list. public class ExerciseOne { public static void main(String []args){ String []colors = {"MAGENTA","RED","WHITE","BLUE","CYAN"}; List<String> list = new ArrayList<String>(); for

问题 I'm writing a quicksort algorithm to sort numbers with random pivot. How can I change my quicksort methods from recursive to iterative? I have one sort method which is recursive, but I need the iterative method. Is it possible to change from recursive to iterative in just the sort method or do I have to change the whole code? here is all my code public class Main { public static void main(String[] args) { long start = System.currentTimeMillis(); ArrayList time = new ArrayList(); for (int k =

问题 I'm writing a quicksort algorithm to sort numbers with random pivot. How can I change my quicksort methods from recursive to iterative? I have one sort method which is recursive, but I need the iterative method. Is it possible to change from recursive to iterative in just the sort method or do I have to change the whole code? here is all my code public class Main { public static void main(String[] args) { long start = System.currentTimeMillis(); ArrayList time = new ArrayList(); for (int k =

问题 My list l has shape np.array(l).shape (100,15,1) It has 100 dataframes with each df having 15 rows and 1 column. The index are same, just the sorting is different in each df of list. I want to unzip the list l: l[0] = Rank l[31] = Rank A1 1 A5 1 A2 2 A1 2 A3 3 A8 3 A4 4.. till 15 A3 4 .... also till 15 I want a single dataframe from this 3-d list l something like this: df= (15,100) 0 1 2 A1 1 2 3 A2 2 3 2 A3 3 6 1 A4 4 4 4 A5 5 8 6 .. till 100 columns and for all 15 indices Basically, a

问题 Can this be done without a loop? import numpy as np n = 10 x = np.random.random(n+1) a, b = 0.45, 0.55 for i in range(n): x = a*x[:-1] + b*x[1:] I came across this setup in another question. There it was a covered by a little obscure nomenclature. I guess it is related to Binomial options pricing model but don't quite understand the topic to be honest. I just was intrigued by the formula and this iterative update / shrinking of x and wondered if it can be done without a loop. But I can not

问题 Can this be done without a loop? import numpy as np n = 10 x = np.random.random(n+1) a, b = 0.45, 0.55 for i in range(n): x = a*x[:-1] + b*x[1:] I came across this setup in another question. There it was a covered by a little obscure nomenclature. I guess it is related to Binomial options pricing model but don't quite understand the topic to be honest. I just was intrigued by the formula and this iterative update / shrinking of x and wondered if it can be done without a loop. But I can not

问题 I have a large database having two dates. E.g. Take superstore data (http://www.tableau.com/sites/default/files/training/global_superstore.zip) 'Orders' Sheet. One date is let's say date of Order and another is date of shipping/delivery (Assume it is delivery date). I want to know details of all orders of those customers who placed their next order without waiting for shipping/delivery of any one of their previous orders. For e.g. Customer with ID 'ZC-21910' placed order with ID CA-2014

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