Develop Reference

How to share random numbers out evenly in C#

I am looking at sharing out a fixed number of 32 teams between a varied number of people.
Of course, 32 may not always be evenly divisible, but for the sake of this exercise, lets say I am looking to share the 32 teams between 4 people, so a maximum number of 8 teams per person.
int max = 32 / numb;
foreach (string value in wcteams)
{
//Assigning teams to players
int selection = random.Next(0, numb);
int[] counter = new int[max];
counter[selection] = counter[selection] + 1;
if (counter[selection] < max)
{
Console.WriteLine(inputtedNames[selection] + " has drawn " + value);
}
}
Right now, I can run that code and I will get a list back of randomly chosen people along with their team. But the limit will not be implemented and some players will end up with more teams than others.
I understand that the following code:
counter[selection] = counter[selection] + 1;
Is not working to add up the number of teams that the user has received, am I on the right track here with how to tally up the number of times a player has been randomly selected or is there another method that I should be doing?

One problem in your code is you are initializing counter inside the loop. Also what happens if the count[selection] > max? you leave the team and don't assign it to anyone else.
Try the following code.
int numb = 4;
int max = 32 / numb;
int[] counter = new int[max];
foreach (string value in wcteams)
{
bool selectionComplete = false;
while(!selectionComplete)
{
int selection = random.Next(0, numb);
counter[selection] = counter[selection] + 1;
if (counter[selection] <= max)
{
selectionComplete = true;
Console.WriteLine(selection + " has drawn " + value);
}
}
}

I cannot figure your code but this should work.
public static Random randomT = new Random();
public static List<List<string>> DivideTeams(string[] teams, int personCount)
{
List<List<string>> divideTeams = new List<List<string>>();
if (teams.Length % personCount != 0)
{
throw new ArgumentOutOfRangeException();
}
//shuffle teams
for(int k = teams.Length -1; k > 0; k--)
{
int trade = random.Next(k + 1);
string temp = teams[trade];
teams[trade] = teams[k];
teams[k] = temp;
}
for (int j = 0; j < personCount; j++)
{
divideTeams.Add(new List<string>());
for (int i = 0; i < teams.Length / personCount; i++)
{
divideTeams[j].Add(teams[i]);
}
}
return divideTeams;
}

Minimum funcion doesn't work as it should

I've written this code with Visual studio c# WindowsForms but it doesn't work as it should.
On my Form1:
private void btnVisualizzaPrezzoMin_Click(object sender, EventArgs e)
{
listView1.Items.Clear();
int i = 0;
while (i < num)
{
if (eleMutui[i].Durata <= int.Parse(txtDurata2.Text) && eleMutui[i].Durata >= int.Parse(txtDurata1.Text))
{
int Min = Funzioni.ImportoMin(eleMutui, num);
ListViewItem Nuovariga = default(ListViewItem);
Nuovariga = new ListViewItem(new string[] {
eleMutui[Min].Codice.ToString(),
eleMutui[Min].Nome,
eleMutui[Min].Provincia,
eleMutui[Min].DataPartenza.ToString(),
eleMutui[Min].Importo.ToString(),
eleMutui[Min].Durata.ToString()
});
listView1.Items.Add(Nuovariga);
}
i++;
}
And the Minimum funcion is:
public static int ImportoMin(Mutui[] ele, int n)
{
int x = 0;
decimal MinimoImporto = default(int);
while (x < n)
{
if (ele[x].Importo < MinimoImporto)
{
MinimoImporto = ele[x].Importo;
}
x++;
}
return decimal.ToInt32(MinimoImporto);
}
Can you help me? I have to do: given by the user a duration interval (ex. between 60 and 120 months), display all the data of the
loan of a lower amount that has a duration in the indicated range.
Thank you!!

It's hard to understand why you use n in ImportoMin(), when you are basically just looping though the []. (That is if n is supposed to be the length of the [], but I don't see where num is declared.)
To continue with your format, you can do something like this:
public static int ImportoMin(Mutui[] ele)
{
decimal MinimoImporto = int.MaxValue;
for(int x = 0; x < ele.length; x++)
{
if (ele[x].Importo < MinimoImporto)
{
MinimoImporto = ele[x].Importo;
}
}
return decimal.ToInt32(MinimoImporto);
}

The issue with your method is that you initialize the min value to zero. Meaning that if all the values in the array are greater than zero then it's going to return zero instead of the actual min. The second issue is that you seem to want the index of the minimum value but you don't keep track of the index and instead return either 0 or the actual min in the array when it's negative (if that's possible). One option is to use MoreLinq's MinBy instead.
var itemWithMinImporto = eleMutui.MinBy(x => x.Importto);
Or you can do that with Linq
var itemWithMinImporto = eleMutui.OrderBy(x=>x.Importto).FirstOrDefault();
Or you can find the index with a normal for loop
int minIndex = -1;
decimal minValue = decimal.MaxValue;
for(int i = 0; i < eleMutui.Length; i++)
{
if(item[i].Importto < minValue)
{
minValue = item[i].Importto;
minIndex = i;
}
}
return minIndex;
Note that it's not clear if n is the actual length of the array or not. If not the above code can be altered to take that into account by using Take(n) for the MoreLinq and Linq solutions or just doing i < n in the for loop.

In your function ImportoMin, instead of using a while loop, you should probably do a for loop instead.
public static int ImportoMin(Mutui[] ele)
{
// I'd return -1 or something to indicate something is wrong
if(ele.Count == 0) return -1;
decimal MinimoImporto = int.MaxValue;
for(int i = 1; i < ele.Length; i++)
{
if( ele[i].Importo < MinimoImporto)
MinimoImporto = ele[i].Importo;
}
return MinimoImporto;
}
In your funciton, you initialize your min to be zero and unless everything else is negative, it will return zero every time.
Edit: This function will return the minimum value in the array, however you can refer to juharr's answer if you're looking for the index.

Find N consecutive integers on a array, whose sum(of consecutive integers) S is a integer that i have

explanation
I have been staring at the problem for a few of minutes.
And i did some research before i ask this quest , but it were in different cases and they didn't included what i really need.
I found this piece of code in SO.
static int GetLargestSum(int[] array, int n, int sum)
{
int largestSum = 0;
int previousSum = 0;
for (int i = 0; i <= array.Length - n; i++)
{
if (i == 0)
{
for (int j = 0; j < n; j++)
{
largestSum += array[j];
}
previousSum = largestSum;
}
else
{
int currentSum = previousSum - array[i - 1] + array[i + n - 1];
if (currentSum > largestSum)
{
largestSum = currentSum;
}
previousSum = currentSum;
}
}
return largestSum;
}
And yes this works but if works for only the largest sum.
I tried to modify it to add the sum var into the code but that didn't actually went that well.
So i would really appreciate if someone helps me, bcs i am stuck in this algorithm.
Thank you!

The way to solve it would be to iterate over each segment of the array and evaluate its sum. A crude first draft would look something like this
public static int ConsecutiveSumArrangements(int[] vals, int count, int sum)
{
var number = 0;
for (int i = 0; i < (vals.Length - count); i++)
{
var segSum = vals.Skip(i).Take(count).Sum();
if (segSum == sum)
{
number++;
}
}
return number;
}

Maybe it is easier think in another way than try to correct this code. An idea is using slide window. Pseudo code look like
sum = 0
sol = 0
start = 0
end = 0
// sum of the first m elements
while end < m
sum = sum + s[end]
end = end + 1
If sum == d
sol = sol + 1
while end < n
sum = sum + s[end]
sum = sum - s[start]
end = end + 1
start = start + 1
if sum == d
sol = sol + 1
// in the loop we add the next element and subtract the first element
//so, we keep the length of m elements

Find the 10001st prime

I took a look at the following question from project euler:
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
What is the 10 001st prime number?
I tried to take the square root of the number and than find all the prime numbers below the square root of the number and then divide the number by all the square roots and see if there is 0 left each time. If the number is not divisible by all the primes under its square root its a prime number. I did this to lower the itterations the programm has to make. Here is what I have now, I am not sure why it isn't working. Anybody knows what i did wrong?
List<int> primeNumbers = new List<int>();
bool prime = true;
bool MainPrime = true;
int check = 1;
for (long i = 3; i < long.MaxValue; i++)
{
if ((i % 2) != 0)
{
int root = Convert.ToInt32(Math.Sqrt(i));
for (int j = 1; j < root; j++)
{
for (int k = 2; k < j; k++)
{
if ((j% k) == 0)
{
prime = false;
}
}
if (prime)
{
primeNumbers.Add(j);
}
prime = true;
}
}
foreach (var item in primeNumbers)
{
if ((i%item) == 0)
{
MainPrime = false;
}
}
primeNumbers.Clear();
if (MainPrime)
{
check++;
}
if (check == 10001)
{
Console.WriteLine(i);
break;
}
}
Console.ReadKey();

Several points:
When finding possible prime divisors, you need to check all numbers up to the square root included, so your condition j < root is incorrect.
You don't have to recalculate the primes again for every number. Keep the list as you go and add new primes to it.
As soon as you find a divisor, you can break out of the foreach loop.
Improved code:
List<long> primeNumbers = new List<long>() { 2 };
for (long i = 3; i < long.MaxValue; i += 2)
{
if(!primeNumbers.Any(p => (i % p) == 0))
{
primeNumbers.Add(i);
if (primeNumbers.Count == 10001)
{
Console.WriteLine(i);
break;
}
}
}
Gives 104743 as the 10001st prime.

What we can do is we can use SieveOfEratosthenes to make an bool array in which all the prime numbers value are set to be true than after that;
1.As we found any prime number increment the count with 1;
2.And as count get equal to 10001 we print its value and break through the loop.
Have a Look at code in C++ (I recommend you to learn SieveOfEratosthenes first)
#include <bits/stdc++.h>
using namespace std;
void SieveOfEratosthenes(long long unsigned n)
{
bool prime[n];
memset(prime, true, sizeof(prime)); //This is SieveOfEratosthenes
for (long long p = 2; p * p <= n; p++)
{
if (prime[p] == true)
{
for (long long i = p * p; i <= n; i += p)
prime[i] = false;
}
}
long long count=0; //initializing count as 0;
for (long long p = 2; p <= n; p++) //running the loop form 2 to n
{
if (prime[p]) //we have bool array in which all prime number set to true using sieve
count++; //increment the count because we found a prime number
if(count==10001) // and as count reaches to 10001 we found our number
{
cout<<p;break;} // print the answer and also break form the loop
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
long long unsigned n=999999;
SieveOfEratosthenes(n); //pass the value of n in sieve function
return 0;
}

Try this one out using python
sp=2
cnt = 1
while cnt <= 10001:
primeflag = 0
for j in range(2,sp):
if(sp%j == 0):
primeflag = 1
break;
if(primeflag == 1):
pass
else:
print(cnt ,sp)
cnt = cnt +1
sp =sp+1
#which Gives
#10001 104743

Help with Creating a Recursive Function C#

I am creating a forecasting application that will run simulations for various "modes" that a production plant is able to run. The plant can run in one mode per day, so I am writing a function that will add up the different modes chosen each day that best maximize the plant’s output and best aligns with the sales forecast numbers provided. This data will be loaded into an array of mode objects that will then be used to calculate the forecast output of the plant.
I have created the functions to do this, however, I need to make them recursive so that I am able to handle any number (within reason) of modes and work days (which varies based on production needs). Listed below is my code using for loops to simulate what I want to do. Can someone point me in the right direction in order to create a recursive function to replace the need for multiple for loops?
Where the method GetNumbers4 would be when there were four modes, and GetNumbers5 would be 5 modes. Int start would be the number of work days.
private static void GetNumber4(int start)
{
int count = 0;
int count1 = 0;
for (int i = 0; 0 <= start; i++)
{
for (int j = 0; j <= i; j++)
{
for (int k = 0; k <= j; k++)
{
count++;
for (int l = 0; l <= i; l++)
{
count1 = l;
}
Console.WriteLine(start + " " + (count1 - j) + " " + (j - k) + " " + k);
count1 = 0;
}
}
start--;
}
Console.WriteLine(count);
}
private static void GetNumber5(int start)
{
int count = 0;
int count1 = 0;
for (int i = 0; 0 <= start; i++)
{
for (int j = 0; j <= i; j++)
{
for (int k = 0; k <= j; k++)
{
for (int l = 0; l <= k; l++)
{
count++;
for (int m = 0; m <= i; m++)
{
count1 = m;
}
Console.WriteLine(start + " " + (count1 - j) + " " + (j - k) + " " + (k - l) + " " + l);
count1 = 0;
}
}
}
start--;
}
Console.WriteLine(count);
}
EDITED:
I think that it would be more helpful if I gave an example of what I was trying to do. For example, if a plant could run in three modes "A", "B", "C" and there were three work days, then the code will return the following results.
3 0 0
2 1 0
2 0 0
1 2 0
1 1 1
1 0 2
0 3 0
0 2 1
0 1 2
0 0 3
The series of numbers represent the three modes A B C. I will load these results into a Modes object that has the corresponding production rates. Doing it this way allows me to shortcut creating a list of every possible combination; it instead gives me a frequency of occurrence.
Building on one of the solutions already offered, I would like to do something like this.
//Where Modes is a custom classs
private static Modes GetNumberRecur(int start, int numberOfModes)
{
if (start < 0)
{
return Modes;
}
//Do work here
GetNumberRecur(start - 1);
}
Thanks to everyone who have already provided input.

Calling GetNumber(5, x) should yield the same result as GetNumber5(x):
static void GetNumber(int num, int max) {
Console.WriteLine(GetNumber(num, max, ""));
}
static int GetNumber(int num, int max, string prefix) {
if (num < 2) {
Console.WriteLine(prefix + max);
return 1;
}
else {
int count = 0;
for (int i = max; i >= 0; i--)
count += GetNumber(num - 1, max - i, prefix + i + " ");
return count;
}
}

A recursive function just needs a terminating condition. In your case, that seems to be when start is less than 0:
private static void GetNumberRec(int start)
{
if(start < 0)
return;
// Do stuff
// Recurse
GetNumberRec(start-1);
}

I've refactored your example into this:
private static void GetNumber5(int start)
{
var count = 0;
for (var i = 0; i <= start; i++)
{
for (var j = 0; j <= i; j++)
{
for (var k = 0; k <= j; k++)
{
for (var l = 0; l <= k; l++)
{
count++;
Console.WriteLine(
(start - i) + " " +
(i - j) + " " +
(j - k) + " " +
(k - l) + " " +
l);
}
}
}
}
Console.WriteLine(count);
}
Please verify this is correct.
A recursive version should then look like this:
public static void GetNumber(int start, int depth)
{
var count = GetNumber(start, depth, new Stack<int>());
Console.WriteLine(count);
}
private static int GetNumber(int start, int depth, Stack<int> counters)
{
if (depth == 0)
{
Console.WriteLine(FormatCounters(counters));
return 1;
}
else
{
var count = 0;
for (int i = 0; i <= start; i++)
{
counters.Push(i);
count += GetNumber(i, depth - 1, counters);
counters.Pop();
}
return count;
}
}
FormatCounters is left as an exercise to the reader ;)

I previously offered a simple C# recursive function here.
The top-most function ends up having a copy of every permutation, so it should be easily adapted for your needs..

I realize that everyone's beaten me to the punch at this point, but here's a dumb Java algorithm (pretty close to C# syntactically that you can try out).
import java.util.ArrayList;
import java.util.List;
/**
* The operational complexity of this is pretty poor and I'm sure you'll be able to optimize
* it, but here's something to get you started at least.
*/
public class Recurse
{
/**
* Base method to set up your recursion and get it started
*
* #param start The total number that digits from all the days will sum up to
* #param days The number of days to split the "start" value across (e.g. 5 days equals
* 5 columns of output)
*/
private static void getNumber(int start,int days)
{
//start recursing
printOrderings(start,days,new ArrayList<Integer>(start));
}
/**
* So this is a pretty dumb recursion. I stole code from a string permutation algorithm that I wrote awhile back. So the
* basic idea to begin with was if you had the string "abc", you wanted to print out all the possible permutations of doing that
* ("abc","acb","bac","bca","cab","cba"). So you could view your problem in a similar fashion...if "start" is equal to "5" and
* days is equal to "4" then that means you're looking for all the possible permutations of (0,1,2,3,4,5) that fit into 4 columns. You have
* the extra restriction that when you find a permutation that works, the digits in the permutation must add up to "start" (so for instance
* [0,0,3,2] is cool, but [0,1,3,3] is not). You can begin to see why this is a dumb algorithm because it currently just considers all
* available permutations and keeps the ones that add up to "start". If you want to optimize it more, you could keep a running "sum" of
* the current contents of the list and either break your loop when it's greater than "start".
*
* Essentially the way you get all the permutations is to have the recursion choose a new digit at each level until you have a full
* string (or a value for each "day" in your case). It's just like nesting for loops, but the for loop actually only gets written
* once because the nesting is done by each subsequent call to the recursive function.
*
* #param start The total number that digits from all the days will sum up to
* #param days The number of days to split the "start" value across (e.g. 5 days equals
* 5 columns of output)
* #param chosen The current permutation at any point in time, may contain between 0 and "days" numbers.
*/
private static void printOrderings(int start,int days,List<Integer> chosen)
{
if(chosen.size() == days)
{
int sum = 0;
for(Integer i : chosen)
{
sum += i.intValue();
}
if(sum == start)
{
System.out.println(chosen.toString());
}
return;
}
else if(chosen.size() < days)
{
for(int i=0; i < start; i++)
{
if(chosen.size() >= days)
{
break;
}
List<Integer> newChosen = new ArrayList<Integer>(chosen);
newChosen.add(i);
printOrderings(start,days,newChosen);
}
}
}
public static void main(final String[] args)
{
//your equivalent of GetNumber4(5)
getNumber(5,4);
//your equivalent of GetNumber5(5)
getNumber(5,5);
}
}