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Algorithm to generate all possible permutations of a list?
...n! possible ways to order these elements. What is an algorithm to generate all possible orderings of this list? Example, I have list [a, b, c]. The algorithm would return [[a, b, c], [a, c, b,], [b, a, c], [b, c, a], [c, a, b], [c, b, a]].
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Rails :dependent => :destroy VS :dependent => :delete_all
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The difference is with the callback.
The :delete_all is made directly in your application and deletes by SQL :
DELETE * FROM users where compagny_id = XXXX
With the :destroy, there is an instantiation of all of your children. So, if you can't destro...
Change Active Menu Item on Page Scroll?
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It's done by binding to the scroll event of the container (usually window).
Quick example:
// Cache selectors
var topMenu = $("#top-menu"),
topMenuHeight = topMenu.outerHeight()+15,
// All list items
menuItems = topMenu.find("a"),
// Anchors corresponding to menu items...
Why does X[Y] join of data.tables not allow a full outer join, or a left join?
...Y) does both ways at the same time. The number of rows of X[Y] and Y[X] usually differ, whereas the number of rows returned by merge(X,Y) and merge(Y,X) is the same.
BUT that misses the main point. Most tasks require something to be done on the
data after a join or merge. Why merge all the co...
Entity Framework - Start Over - Undo/Rollback All Migrations
...oint where I just want to start over, so is there a way to completely undo all migrations, erase the history, and delete the migration code, so I'm back to square one?
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Getting error: Peer authentication failed for user “postgres”, when trying to get pgsql working with
....conf file (/etc/postgresql/9.1/main/pg_hba.conf*).
This line:
local all postgres peer
Should be:
local all postgres md5
* If you can't find this file, running locate pg_hba.conf should show you where ...
Copy all files with a certain extension from all subdirectories
Under unix, I want to copy all files with a certain extension (all excel files) from all subdirectories to another directory. I have the following command:
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navbar color in Twitter Bootstrap
...or of the navbar of the Twitter Bootstrap 2.0.2? How can I change color of all the elements of the navbar to reflect the background color?
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Are there console commands to look at whats in the queue and to clear the queue in Sidekiq?
... that there are methods just for viewing the queued jobs, but they would really just be wrappers around Redis commands, since that's basically all Sidekiq (and Resque) is:
# See workers
Sidekiq::Client.registered_workers
# See queues
Sidekiq::Client.registered_queues
# See all jobs for one queue
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How do I replace text in a selection?
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This frustrated the heck out of me, and none of the above answers really got me what I wanted. I finally found the answer I was looking for, on a mac if you do ⌘ + option + F it will bring up a Find-Replace bar at the bottom of your editor which is local to the file you have open.
There is...