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Knight's Shortest Path on Chessboard
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You have a graph here, where all available moves are connected (value=1), and unavailable moves are disconnected (value=0), the sparse matrix would be like:
(a1,b3)=1,
(a1,c2)=1,
.....
And the shortest path of two points in a graph can be found usin...
What is the difference between 'my' and 'our' in Perl?
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On the other hand, our variables are package variables, and thus automatically:
global variables
definitely not private
not necessarily new
can be accessed outside the package (or lexical scope) with the
qualified namespace, as $package_name::variable.
Declaring a variable with our allows you...
indexOf method in an object array?
... think to see the performance of this method vs. a simple for loop. Especially when you're running on a mobile platform with limited resources.
– Doug
Aug 17 '15 at 5:51
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Access denied for user 'root'@'localhost' while attempting to grant privileges. How do I grant privi
... basics. Though of course, that doesn't mean I haven't missed something totally obvious. :-)
13 Answers
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Querying DynamoDB by date
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Updated Answer:
DynamoDB allows for specification of secondary indexes to aid in this sort of query. Secondary indexes can either be global, meaning that the index spans the whole table across hash keys, or local meaning that the index would exist w...
PHP mkdir: Permission denied problem
...te permissions on the directory.
Here's what you do in Ubuntu
Make sure all files are owned by the Apache group and user. In Ubuntu it is the www-data group and user
chown -R www-data:www-data /path/to/webserver/www
Next enabled all members of the www-data group to read and write files
chmod -R...
How to change collation of database, table, column?
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You need to either convert each table individually:
ALTER TABLE mytable CONVERT TO CHARACTER SET utf8mb4
(this will convert the columns just as well), or export the database with latin1 and import it back with utf8mb4.
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What is “:-!!” in C code?
...sizeof(struct { int: -!!(e); }))
(e): Compute expression e.
!!(e): Logically negate twice: 0 if e == 0; otherwise 1.
-!!(e): Numerically negate the expression from step 2: 0 if it was 0; otherwise -1.
struct{int: -!!(0);} --> struct{int: 0;}: If it was zero, then we declare a struct with an an...
Force SSL/https using .htaccess and mod_rewrite
...that expose stuff that should be protected. When this directive is present all requests are denied which are not using SSL.
This will not do a redirect to https though. To redirect, try the following with mod_rewrite in your .htaccess file
RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^ ...
Get all unique values in a JavaScript array (remove duplicates)
...l loop through the array and leave only those entries that pass the given callback function onlyUnique.
onlyUnique checks, if the given value is the first occurring. If not, it must be a duplicate and will not be copied.
This solution works without any extra library like jQuery or prototype.js.
It w...