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Best algorithm for detecting cycles in a directed graph [closed]
...grey (current node is visited but all reachable nodes are not yet visited) and black (all reachable nodes are visited along with the current one) color coding, if a grey node finds another grey node then we've a cycle. [Pretty much what we've in Cormen's algorithm book]. Wondering if 'Tarjan's algor...
How do I watch a file for changes?
...ons to this problem have been posted here as well.
– Anderson Green
Aug 13 '13 at 22:53
Is there a benchmark, if this ...
How assignment works with Python list slice?
...lar syntax:
1) slicing:
b = a[0:2]
This makes a copy of the slice of a and assigns it to b.
2) slice assignment:
a[0:2] = b
This replaces the slice of a with the contents of b.
Although the syntax is similar (I imagine by design!), these are two different operations.
...
Why does “_” (underscore) match “-” (hyphen)?
... SQL pattern matching enables you to use "_" to match any single character and "%" to match an arbitrary number of characters (including zero characters).
(From section 3.3.4.7. Pattern Matching in the MySQL documentation.)
If you want to use the underscore in like as a literal, you have to escap...
How to remove from a map while iterating it?
...
The standard associative-container erase idiom:
for (auto it = m.cbegin(); it != m.cend() /* not hoisted */; /* no increment */)
{
if (must_delete)
{
m.erase(it++); // or "it = m.erase(it)" since C++11
}
else
{
...
MD5 algorithm in Objective-C
...
md5 is available on the iPhone and can be added as an addition for ie NSString and NSData like below.
MyAdditions.h
@interface NSString (MyAdditions)
- (NSString *)md5;
@end
@interface NSData (MyAdditions)
- (NSString*)md5;
@end
MyAdditions.m
#import...
Circular list iterator in Python
...
(Loops forever, obviously)
In order to manually advance the iterator and pull values from it one by one, simply call next(pool):
>>> next(pool)
'a'
>>> next(pool)
'b'
share
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...
python exception message capturing
... 2.x
logger.error('Failed to upload to ftp: '+ str(e))
in Python 3.x and modern versions of Python 2.x use except Exception as e instead of except Exception, e:
try:
with open(filepath,'rb') as f:
con.storbinary('STOR '+ filepath, f)
logger.info('File successfully uploaded to ...
How do I get a list of column names from a psycopg2 cursor?
...ral way to generate column labels directly from the selected column names, and recall seeing that python's psycopg2 module supports this feature.
...
Why are preprocessor macros evil and what are the alternatives?
...d encountered a phrase like "macro should never be used", "macro are evil" and so on, my question is: why? With the new C++11 is there a real alternative after so many years?
...