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What is memoization and how can I use it in Python?
...orials using memoization in Python would be something like this:
factorial_memo = {}
def factorial(k):
if k < 2: return 1
if k not in factorial_memo:
factorial_memo[k] = k * factorial(k-1)
return factorial_memo[k]
You can get more complicated and encapsulate the memoization...
Getting the last argument passed to a shell script
...
The simplest answer for bash 3.0 or greater is
_last=${!#} # *indirect reference* to the $# variable
# or
_last=$BASH_ARGV # official built-in (but takes more typing :)
That's it.
$ cat lastarg
#!/bin/bash
# echo the last arg given:
_last=${!#}
echo $_last
_last...
Collapse sequences of white space into a single character and trim string
... d*mn line endings and auto-format... it doesn't deal with "hello______foo" (assume _ -> " " because formatting comments is hard)
– Brian Postow
Sep 15 '09 at 14:11
32...
What is the _snowman param in Ruby on Rails 3 forms for?
...n Ruby on Rails 3 (currently using Beta 4), I see that when using the form_tag or form_for helpers there is a hidden field named _snowman with the value of ☃ ( Unicode \x9731) showing up.
...
What should my Objective-C singleton look like? [closed]
... below, I think you should be doing:
+ (id)sharedFoo
{
static dispatch_once_t once;
static MyFoo *sharedFoo;
dispatch_once(&once, ^ { sharedFoo = [[self alloc] init]; });
return sharedFoo;
}
share
...
What do the terms “CPU bound” and “I/O bound” mean?
...:
#define SIZE 1000000000
unsigned int is[SIZE];
unsigned int sum = 0;
size_t i = 0;
for (i = 0; i < SIZE; i++)
/* Each one of those requires a RAM access! */
sum += is[i]
Parallelizing that by splitting the array equally for each of your cores is of limited usefulness on common modern d...
How do I check if a string contains another string in Swift?
... and containsIgnoringCase for String
extension String {
func contains(_ find: String) -> Bool{
return self.range(of: find) != nil
}
func containsIgnoringCase(_ find: String) -> Bool{
return self.range(of: find, options: .caseInsensitive) != nil
}
}
Older Swift vers...
Adding a cross-reference to a subheading or anchor in another page
... general :ref: directive, documented here. They give this example:
.. _my-reference-label:
Section to cross-reference
--------------------------
This is the text of the section.
It refers to the section itself, see :ref:`my-reference-label`.
Although the general hyperlinkin...
Javascript/DOM: How to remove all events of a DOM object?
...the returned function and create some weird removeAllEvents function:
var _eventHandlers = {}; // somewhere global
const addListener = (node, event, handler, capture = false) => {
if (!(event in _eventHandlers)) {
_eventHandlers[event] = []
}
// here we track the events and their node...
Why is there no xrange function in Python3?
...tion has nothing to do with it. (Not surprising, as a one-time call to the __iter__ slot isn't likely to be visible among 10000000 calls to whatever happens in the loop, but someone brought it up as a possibility.)
But it's only 30% slower. How did the OP get 2x as slow? Well, if I repeat the same ...