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Algorithms based on number base systems? [closed]
...s (systems that have more than one representation of a number) are useful.
If you arrange the first digit to be non-zero or use a zeroless representation, retrieving the head of the data structure can be efficient.
Avoid cascading borrows (from taking the tail of the list) and carries (from consing ...
What is the most efficient way of finding all the factors of a number in Python?
...st.__add__,
([i, n//i] for i in range(1, int(n**0.5) + 1) if n % i == 0)))
This will return all of the factors, very quickly, of a number n.
Why square root as the upper limit?
sqrt(x) * sqrt(x) = x. So if the two factors are the same, they're both the square root. If you make o...
Dictionaries and default values
...
+1 for readability, but if/else is much faster. That might or might not play a role.
– Tim Pietzcker
Jul 6 '13 at 9:20
...
Logical operators for boolean indexing in Pandas
...ear when it should be True or False. Some users might assume they are True if they have non-zero length, like a Python list. Others might desire for it to be True only if all its elements are True. Others might want it to be True if any of its elements are True.
Because there are so many conflicti...
PHP Regex to check date is in YYYY-MM-DD format
...
Try this.
$date="2012-09-12";
if (preg_match("/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/",$date)) {
return true;
} else {
return false;
}
share
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...
How to convert an xml string to a dictionary?
...:
def __init__(self, aList):
for element in aList:
if element:
# treat like dict
if len(element) == 1 or element[0].tag != element[1].tag:
self.append(XmlDictConfig(element))
# treat like list
...
C++: Rounding up to the nearest multiple of a number
OK - I'm almost embarrassed posting this here (and I will delete if anyone votes to close) as it seems like a basic question.
...
How to represent multiple conditions in a shell if statement?
...
Classic technique (escape metacharacters):
if [ \( "$g" -eq 1 -a "$c" = "123" \) -o \( "$g" -eq 2 -a "$c" = "456" \) ]
then echo abc
else echo efg
fi
I've enclosed the references to $g in double quotes; that's good practice, in general. Strictly, the parentheses ar...
Bash if statement with multiple conditions throws an error
...ion. So your script would be like this:
my_error_flag=1
my_error_flag_o=1
if [ $my_error_flag -eq 1 ] || [ $my_error_flag_o -eq 2 ] || ([ $my_error_flag -eq 1 ] && [ $my_error_flag_o -eq 2 ]); then
echo "$my_error_flag"
else
echo "no flag"
fi
Although in your case you can disca...
Definition of a Balanced Tree
I am just wondering if someone might be able to clarify the definition of a balanced tree for me. I have that "a tree is balanced if each sub-tree is balanced and the height of the two sub-trees differ by at most one.
...