I have a short code which I can't seem to figure out. The biggest problem which I have is that I don't understand the error and cannot seem to find how I can change the type of my array.
int [][] spawnLocatiesCoins = new int [20][2];
void collectenVanCoins () {
if (gameState == 1) {
for (int i = 0; i<10; i++) {
if (key == 's' && dist(spawnLocatiesCoins[i][0], spawnLocatiesCoins[i][1], xPosPlayer1, yPosPlayer1) < 20) {
println("catch" + i);
score++;
spawnLocatiesCoins.splice(i, 1);
}
}
}
}
What I am trying to do is remove the spawnLocationsCoins[i] from my array. The error message which I get here is Cannot invoke splice(int, int) on the array type int[][]. I have tried several different approaches for the splice method. I have also tried using the remove method with no result.
Could someone explain to me how I can remove an item from a int [][] array.
You are probably trying to use Processing splice function, however, that doesn't do what you want ("Inserts a value or an array of values into an existing array").
I'd say you are best off using an ArrayList instead of an array, where you can then just use the .remove function like this:
list.remove(index);
Because you want to store 2 values (x and y), you could make an ArrayList of int arrays
ArrayList<int[]> spawnLocatiesCoins = new ArrayList<int[]>();
You can add values like this:
spawnLocatiesCoins.add(new int[]{x_value, y_value});
And access them like this:
spawnLocatiesCoins.get(index)[index_in_the_array];
You could also use PVectors (variables that can store 2/3 values (depending on whether you are making a 3D program)) instead of arrays, but you probably don't need them at this point.
Hi guys I am really stuck in this one situation :S I have a local .txtfile with a random sentence and my program is meant to :
I am finding it difficult to execute the third question. My code is ..
JavaScript
lengths.forEach((leng) => {
counter[leng] = counter[leng] || 0;
counter[leng]++;
});
$("#display_File_most").text(counter);
}
}
r.readAsText(f);
}
});
</script>
I have used this question for help but no luck - Using Javascript to find most common words in string?
I believe I have to store the sentence in an array and loop through it, uncertain if that is the correct step or if there is quicker way of finding the solution so I ask you guys.
Thanks for your time & I hope my question made sense :)
If you think of your solution as separated well done tasks, it would be really simple to find it. Here you have them together:
Convert the words into an array. Your guts were right about this :)
var source = "Hello world & good morning. The date is 18/09/2018";
var words = source.split(' ');
The next step is to find out the length of each word
var lengths = words.map(function(word) {
return word.length;
});
Finally the most complicated part is to get the number of occurrences for each length. One idea is to use an object to use key/value where key is the length and value is its count (source: https://stackoverflow.com/a/10541220/1505348)
Now you will see under the counter object have each word length with its repetition number on the source string.
var source = "Hello world & good morning. The date is 18/09/2018";
var words = source.split(' ');
var lengths = words.map(function(word) {
return word.length;
});
var counter = {};
lengths.forEach((leng) => {
counter[leng] = counter[leng] || 0;
counter[leng]++;
});
console.log(counter);
3.Produce a list of number of words of each length in sentence (not done).
Based on the question would this not be the solution?
var words = str.split(" ");
var count = {};
for (var i = 0; i<words.length; i++){
count[words[i].length] = (count [words[i].length] || 0) + 1
}
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I am creating bunch of unique codes in order to run a promotional campaign.
The campaign will run for a total of 20 million unique items. The validity of the code will be one year. I am currently looking for best possible option.
I can use only 0-9 and A-Z in the code. so that limits me to using 36 unique characters in my code. The end user will need to key in the unique cd in the system and get offers. The unique code will not be tied against any user or transaction to begin with.
One way to generate unique code is create incremental numbers and then convert them to base36 to get a unique cd. The problem with this is that its easily hackable. Users can start inserting unqiue cd in incremental fashion and redeem offers not meant for them. I am thinking of introducing some kind of randomisation. Need suggestions regarding the same.
Note - The limit of max characters in the code is 8.
Use a cryptographically strong random number generator to generate 40-bit numbers (i.e. sequences of 5-byte random arrays). Converting each array to base-36 will yield a sequence of random eight-character codes. Run an additional check on each code to make sure that there are no duplicates. Using a hash set on the converted strings will let you perform this task in a reasonable time.
Here is an example implementation in Java:
Set<String> codes = new HashSet<>();
SecureRandom rng = new SecureRandom();
byte[] data = new byte[5];
for (int i = 0 ; i != 100000 ; i++) {
rng.nextBytes(data);
long val = ((long)(data[0] & 0xFF))
| (((long)(data[1] & 0xFF)) << 8)
| (((long)(data[2] & 0xFF)) << 16)
| (((long)(data[3] & 0xFF)) << 24)
| (((long)(data[4] & 0xFF)) << 32);
String s = Long.toString(val, 36);
codes.add(s);
}
System.out.println("Generated "+codes.size()+" codes.");
Demo.
Use a Guid (C# code):
string code = Guid.NewGuid().ToString().Substring(0,8).ToUpperInvariant();
Since we have a hexadecimal representation we get digits and the characters a to f. We get 16^8 possible codes which is > 4 billion codes. One every 214 for 20 million codes.
Guid.NewGuid().ToString() yields a string like "6b984c2f-5866-4745-ac34-d5088a56070f". Since the first group has a length of 8 characters we can just take the first 8 chars and convert them to upper case. The result looks like "6B984C2F".
Note that this can yield duplicate codes. We can avoid this like this:
var codes = new HashSet<string>();
while (codes.Count < 20000000) {
string code = Guid.NewGuid().ToString().Substring(0,8).ToUpperInvariant();
codes.Add(code);
}
The HashSet allows you to add an item more than once but always only keeps one of them. (Just as math sets.)
If you want to use the full range of possible values the one-liner from above does not do it. With the whole alphabet plus digits we get 36^8 = ~2.8 * 10^12 possible codes. One every 141,055 for 20 million codes. That's better but still not completely hack proof. You will need to limit the number of entry attempts, use a CAPTCHA etc.
const string Base = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const int CodeLength = 8;
const int NumCodes = 20000000;
var random = new Random();
var codes = new HashSet<string>();
var chars = new char[CodeLength];
while (codes.Count < NumCodes) {
for (int i = 0; i < CodeLength; i++) {
int pos = random.Next(Base.Length);
chars[i] = Base[pos];
}
string code = new string(chars);
codes.Add(code);
}
I need to generate a unique id with a limit of 6 blocks. That id should contains letters in upper case and number.
How can I do it? I thougth in use the date, but I'm failed.
More details...
That Id just need not repeat, but should be generate alone, whithout base in a last sequence.
I can do this in any language.
I made a blog post to generate a strong SQL Server password. You can adapt this to what you need. For a better format blog post here.
We have the requirement that our passwords have to change every 90 days. I wanted to automate this and it sounded pretty easy to do, but it wasn’t that easy. Why? Because there are a lot of rules for passwords.
First, I have to store it in the web.config. So no XML special characters.
quot "
amp &
apos '
lt <
gt >
Next, If used in an OLE DB or ODBC connection string, a password must not contain the following characters: [] {}() , ; ? * ! #.
Finally, strong passwords must contains characters from at least three of the following categories:
English uppercase characters (A through Z)
English lowercase characters (a through z)
Base 10 digits (0 through 9)
Nonalphabetic characters (for example: !, $, #, %)
So keeping all of these rules in mind I created a simple class. that I can just call
public class PasswordGenerator
{
private static string CHARS_LCASE = "abcdefgijkmnopqrstwxyz";
private static string CHARS_UCASE = "ABCDEFGHJKLMNPQRSTWXYZ";
private static string CHARS_NUMERIC = "23456789";
private static string CHARS_SPECIAL = "*-+_%/";
private static string CHARS_ALL = CHARS_LCASE + CHARS_UCASE + CHARS_NUMERIC + CHARS_SPECIAL;
public static string GeneratePassword(int length)
{
char[] chars = new char[length];
Random rand = new Random();
for (int i = 0; i < length; i++)
{
switch (i)
{
case 0:
chars[i] = CHARS_LCASE[rand.Next(0, CHARS_LCASE.Length)];
break;
case 1:
chars[i] = CHARS_UCASE[rand.Next(0, CHARS_UCASE.Length)];
break;
case 2:
chars[i] = CHARS_NUMERIC[rand.Next(0, CHARS_NUMERIC.Length)];
break;
case 3:
chars[i] = CHARS_SPECIAL[rand.Next(0, CHARS_SPECIAL.Length)];
break;
default:
chars[i] = CHARS_ALL[rand.Next(0, CHARS_ALL.Length)];
break;
}
}
return new string(chars);
}
}
So now I just simply call this for a new password:
PasswordGenerator.GeneratePassword(13)
This is a bit of a side project I have taken on to solve a no-fix issue for work. Our system outputs a code to represent a combination of things on another thing. Some example codes are:
9-9-0-4-4-5-4-0-2-0-0-0-2-0-0-0-0-0-2-1-2-1-2-2-2-4
9-5-0-7-4-3-5-7-4-0-5-1-4-2-1-5-5-4-6-3-7-9-72
9-15-0-9-1-6-2-1-2-0-0-1-6-0-7
The max number in one of the slots I've seen so far is about 150 but they will likely go higher.
When the system was designed there was no requirement for what this code would look like. But now the client wants to be able to type it in by hand from a sheet of paper, something the code above isn't suited for. We've said we won't do anything about it, but it seems like a fun challenge to take on.
My question is where is a good place to start loss-less compressing this code? Obvious solutions such as store this code with a shorter key are not an option; our database is read only. I need to build a two way method to make this code more human friendly.
1) I agree that you definately need a checksum - data entry errors are very common, unless you have really well trained staff and independent duplicate keying with automatic crosss-checking.
2) I suggest http://en.wikipedia.org/wiki/Huffman_coding to turn your list of numbers into a stream of bits. To get the probabilities required for this, you need a decent sized sample of real data, so you can make a count, setting Ni to the number of times number i appears in the data. Then I suggest setting Pi = (Ni + 1) / (Sum_i (Ni + 1)) - which smooths the probabilities a bit. Also, with this method, if you see e.g. numbers 0-150 you could add a bit of slack by entering numbers 151-255 and setting them to Ni = 0. Another way round rare large numbers would be to add some sort of escape sequence.
3) Finding a way for people to type the resulting sequence of bits is really an applied psychology problem but here are some suggestions of ideas to pinch.
3a) Software licences - just encode six bits per character in some 64-character alphabet, but group characters in a way that makes it easier for people to keep place e.g. BC017-06777-14871-160C4
3b) UK car license plates. Use a change of alphabet to show people how to group characters e.g. ABCD0123EFGH4567IJKL...
3c) A really large alphabet - get yourself a list of 2^n words for some decent sized n and encode n bits as a word e.g. GREEN ENCHANTED LOGICIAN... -
i worried about this problem a while back. it turns out that you can't do much better than base64 - trying to squeeze a few more bits per character isn't really worth the effort (once you get into "strange" numbers of bits encoding and decoding becomes more complex). but at the same time, you end up with something that's likely to have errors when entered (confusing a 0 with an O etc). one option is to choose a modified set of characters and letters (so it's still base 64, but, say, you substitute ">" for "0". another is to add a checksum. again, for simplicity of implementation, i felt the checksum approach was better.
unfortunately i never got any further - things changed direction - so i can't offer code or a particular checksum choice.
ps i realised there's a missing step i didn't explain: i was going to compress the text into some binary form before encoding (using some standard compression algorithm). so to summarize: compress, add checksum, base64 encode; base 64 decode, check checksum, decompress.
This is similar to what I have used in the past. There are certainly better ways of doing this, but I used this method because it was easy to mirror in Transact-SQL which was a requirement at the time. You could certainly modify this to incorporate Huffman encoding if the distribution of your id's is non-random, but it's probably unnecessary.
You didn't specify language, so this is in c#, but it should be very easy to transition to any language. In the lookup you'll see commonly confused characters are omitted. This should speed up entry. I also had the requirement to have a fixed length, but it would be easy for you to modify this.
static public class CodeGenerator
{
static Dictionary<int, char> _lookupTable = new Dictionary<int, char>();
static CodeGenerator()
{
PrepLookupTable();
}
private static void PrepLookupTable()
{
_lookupTable.Add(0,'3');
_lookupTable.Add(1,'2');
_lookupTable.Add(2,'5');
_lookupTable.Add(3,'4');
_lookupTable.Add(4,'7');
_lookupTable.Add(5,'6');
_lookupTable.Add(6,'9');
_lookupTable.Add(7,'8');
_lookupTable.Add(8,'W');
_lookupTable.Add(9,'Q');
_lookupTable.Add(10,'E');
_lookupTable.Add(11,'T');
_lookupTable.Add(12,'R');
_lookupTable.Add(13,'Y');
_lookupTable.Add(14,'U');
_lookupTable.Add(15,'A');
_lookupTable.Add(16,'P');
_lookupTable.Add(17,'D');
_lookupTable.Add(18,'S');
_lookupTable.Add(19,'G');
_lookupTable.Add(20,'F');
_lookupTable.Add(21,'J');
_lookupTable.Add(22,'H');
_lookupTable.Add(23,'K');
_lookupTable.Add(24,'L');
_lookupTable.Add(25,'Z');
_lookupTable.Add(26,'X');
_lookupTable.Add(27,'V');
_lookupTable.Add(28,'C');
_lookupTable.Add(29,'N');
_lookupTable.Add(30,'B');
}
public static bool TryPCodeDecrypt(string iPCode, out Int64 oDecryptedInt)
{
//Prep the result so we can exit without having to fiddle with it if we hit an error.
oDecryptedInt = 0;
if (iPCode.Length > 3)
{
Char[] Bits = iPCode.ToCharArray(0,iPCode.Length-2);
int CheckInt7 = 0;
int CheckInt3 = 0;
if (!int.TryParse(iPCode[iPCode.Length-1].ToString(),out CheckInt7) ||
!int.TryParse(iPCode[iPCode.Length-2].ToString(),out CheckInt3))
{
//Unsuccessful -- the last check ints are not integers.
return false;
}
//Adjust the CheckInts to the right values.
CheckInt3 -= 2;
CheckInt7 -= 2;
int COffset = iPCode.LastIndexOf('M')+1;
Int64 tempResult = 0;
int cBPos = 0;
while ((cBPos + COffset) < Bits.Length)
{
//Calculate the current position.
int cNum = 0;
foreach (int cKey in _lookupTable.Keys)
{
if (_lookupTable[cKey] == Bits[cBPos + COffset])
{
cNum = cKey;
}
}
tempResult += cNum * (Int64)Math.Pow((double)31, (double)(Bits.Length - (cBPos + COffset + 1)));
cBPos += 1;
}
if (tempResult % 7 == CheckInt7 && tempResult % 3 == CheckInt3)
{
oDecryptedInt = tempResult;
return true;
}
return false;
}
else
{
//Unsuccessful -- too short.
return false;
}
}
public static string PCodeEncrypt(int iIntToEncrypt, int iMinLength)
{
int Check7 = (iIntToEncrypt % 7) + 2;
int Check3 = (iIntToEncrypt % 3) + 2;
StringBuilder result = new StringBuilder();
result.Insert(0, Check7);
result.Insert(0, Check3);
int workingNum = iIntToEncrypt;
while (workingNum > 0)
{
result.Insert(0, _lookupTable[workingNum % 31]);
workingNum /= 31;
}
if (result.Length < iMinLength)
{
for (int i = result.Length + 1; i <= iMinLength; i++)
{
result.Insert(0, 'M');
}
}
return result.ToString();
}
}