Your first example should be O(N log N) as set takes log N time for each insertion. I don’t think a faster O is possible. The second example is obviously O(N^2). The coefficient and memory usage are low, so it might be faster (or even the fastest) in some cases. It depends what T is, … Read more
There is no “error” if you use more than one key with the same name, but in JSON, the last key with the same name is the one that is going to be used. In your case, the key “name” would be better to contain an array as it’s value, instead of having a number … Read more
array = [[‘a’,’b’], [‘a’, ‘b’,’c’], [‘a’]] result = {x for l in array for x in l}
Unless you acquire a lock on a whole table, it is basically not possible to check for unicity using a SQL query (any concurrent transaction could modify data after a manual check but before the commit of the ongoing transaction). In other words, it isn’t possible to implement a valid unique verification at the Java … Read more
ALTER TABLE your_table DROP INDEX user_id, ADD UNIQUE KEY `user_id` (`user_id`,`account_id`,`pet_id`)
Did you add the Select() after the Where() or before? You should add it after, because of the concurrency logic: 1 Take the entire table 2 Filter it accordingly 3 Select only the ID’s 4 Make them distinct. If you do a Select first, the Where clause can only contain the ID attribute because all … Read more
Add a unique constraint for that column: ALTER TABLE Foo ADD CONSTRAINT UQ_Name UNIQUE (Name) To add it through SQL Management Studio UI: Open SQL Server Management Studio. Expand the Tables folder of the database where you wish to create the constraint. Right-click the table where you wish to add the constraint and click Design. … Read more
To count the number of different values in A2:A100 (not counting blanks): =SUMPRODUCT((A2:A100<>””)/COUNTIF(A2:A100,A2:A100&””)) Copied from an answer by @Ulli Schmid to What is this COUNTIF() formula doing?: =SUMPRODUCT((A1:A100<>””)/COUNTIF(A1:A100,A1:A100&””)) Counts unique cells within A1:A100, excluding blank cells and ones with an empty string (“”). How does it do that? Example: A1:A100 = [1, 1, 2, “apple”, … Read more
Just use: $output = array_merge($array1, $array2); That should solve it. Because you use string keys if one key occurs more than one time (like ’44’ in your example) one key will overwrite preceding ones with the same name. Because in your case they both have the same value anyway it doesn’t matter and it will … Read more