It is an performance optimization for both time and memory. The ReverseRandomAccessCollection presents the elements of the original array in reverse order, without the need to create a new array and copying all elements (as long as the original array is not mutated). You can access the reversed elements with subscripts: let el0 = arr[arr.startIndex] … Read more
This doesn’t generalize the links, but does solve the problem: Go through all the arrays and if any have length > k, truncate to length k (this is silly, but we’ll mess with k later, so do it anyway) Identify the largest remaining array A. If more than one, pick one. Pick the middle element … Read more
Use concat_ws(string delimiter, array<string>) function to concatenate array: select actor, concat_ws(‘,’,collect_set(date)) as grpdate from actor_table group by actor; If the date field is not string, then convert it to string: concat_ws(‘,’,collect_set(cast(date as string))) Read also this answer about alternative ways if you already have an array (of int) and do not want to explode it … Read more
I would not advice to use the method requestAction but rather import, and instantiate the needed controller. CakePHP doc says about requestAction that: “It is rarely appropriate to use in a controller or model” http://book.cakephp.org/view/434/requestAction Once you imported and loaded the controller you can call any method of this controller with its parameters. <?php //Import … Read more
vector(indecies) = [] example: >> a = 1:10; >> a([3,4,7]) = [] a = 1 2 5 6 8 9 10
You can use a dynamic array when you don’t know the number of values it will contain until run-time: Dim Zombies() As Integer ReDim Zombies(NumberOfZombies) Or you could do everything with one statement if you’re creating an array that’s local to a procedure: ReDim Zombies(NumberOfZombies) As Integer Fixed-size arrays require the number of elements contained … Read more
Dynamic programming? Given an array A[0..n], let M(i) be the optimal solution using the elements with indices 0..i. Then M(-1) = 0 (used in the recurrence), M(0) = A[0], and M(i) = max(M(i – 1), M(i – 2) + A[i]) for i = 1, …, n. M(n) is the solution we want. This is O(n). … Read more
Your function doesn’t work because PowerShell returns all non-captured stream output, not just the argument of the return statement. An empty array is mangled into $null in the process. However, you can preserve an array on return by prepending it with the array construction operator (,): function test { $arr = @() return ,$arr }
Tongue-in-cheek O(NlogN) solution Perform an FFT on your string (treating characters as numeric values). Every peak in the resulting graph corresponds to a substring periodicity.
As of MongoDB v2.5.3, there is a new $position operator that you can include along with the $each operator as part of your $push query to specify the location in the array at which you would like to insert a value. Here’s an example from the docs page to add the elements 20 and 30 … Read more