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Designing function f(f(n)) == -n
...w about:
f(n) = sign(n) - (-1)n * n
In Python:
def f(n):
if n == 0: return 0
if n >= 0:
if n % 2 == 1:
return n + 1
else:
return -1 * (n - 1)
else:
if n % 2 == 1:
return n - 1
else:
return -1 * (n ...
Error to install Nokogiri on OSX 10.9 Maverick?
...
30 Answers
30
Active
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Get Slightly Lighter and Darker Color from UIColor
...
280
- (UIColor *)lighterColorForColor:(UIColor *)c
{
CGFloat r, g, b, a;
if ([c getRed:&...
How to iterate through two lists in parallel?
... |
edited Jun 9 '19 at 20:46
Tobias Kolb
9461111 silver badges2626 bronze badges
answered Nov 2 '09 at...
How do you detect Credit card type based on number?
...
+50
The credit/debit card number is referred to as a PAN, or Primary Account Number. The first six digits of the PAN are taken from the I...
How to find the kth smallest element in the union of two sorted arrays?
...
50
You've got it, just keep going! And be careful with the indexes...
To simplify a bit I'll assum...
What's the (hidden) cost of Scala's lazy val?
...uivalent to the following Java code:
class LazyTest {
public int bitmap$0;
private String msg;
public String msg() {
if ((bitmap$0 & 1) == 0) {
synchronized (this) {
if ((bitmap$0 & 1) == 0) {
synchronized (this) {
msg = "La...
How do I base64 encode (decode) in C?
...
106
Here's the one I'm using:
#include <stdint.h>
#include <stdlib.h>
static char en...
Fast Bitmap Blur For Android SDK
... I'm looping through the pixels of an image to blur it. This takes about 30 seconds on a 640x480 image.
19 Answers
...
How to check if a number is a power of 2
...his problem:
bool IsPowerOfTwo(ulong x)
{
return (x & (x - 1)) == 0;
}
Note, this function will report true for 0, which is not a power of 2. If you want to exclude that, here's how:
bool IsPowerOfTwo(ulong x)
{
return (x != 0) && ((x & (x - 1)) == 0);
}
Explanation
Fi...