Develop Reference

Digit difference sort

So I am trying to solve this task "Digit Difference Sort" on Codefights
Given an array of integers, sort its elements by the difference of their largest and smallest digits.
In the case of a tie, that with the larger index in the array should come first.
Example
For a = [152, 23, 7, 887, 243], the output should be digitDifferenceSort(a) = [7, 887, 23, 243, 152].
Here are the differences of all the numbers:
152: difference = 5 - 1 = 4;
23: difference = 3 - 2 = 1;
7: difference = 7 - 7 = 0;
887: difference = 8 - 7 = 1;
243: difference = 4 - 2 = 2.
23 and 887 have the same difference, but 887 goes after 23 in a, so in the sorted array it comes first.
I have an issue with two numbers having the same difference. Here's what I wrote so far:
int[] digitDifferenceSort(int[] a) {
return a.OrderBy(x => difference(x)).ToArray();
}
int difference(int x)
{
int min = 9, max = 0;
do
{
int tmp = x % 10;
min = Math.Min(min, tmp);
max = Math.Max(max, tmp);
} while ((x /= 10) > 0);
return max - min;
}
Didn't do much (for example the output is still [7, 23, 887, 243, 152] rather than [7, 887, 23, 243, 152])
How do I make element with larger index come first in result? What should I use instead of OrderBy?

I don't consider your difference method, i assume it works fine.
To your question: you have to keep revered order of the array (that the items with the same difference arrive will be sorted reverse). To do it, you could just reverse you input array: all items with not identical difference will be ordered correctly, and with the same differece will be ordered reversed:
int[] digitDifferenceSort(int[] a)
{
return a.Reverse().OrderBy(x => difference(x)).ToArray();
}

Following is my code for the above question digit difference sort. I am also getting output when running in Eclipse but when I paste the code on code signal it gives me a null pointer exception.
package NormalPrograms;
import java.util.ArrayList;
import java.util.Collections;
public class DigitDifferenceSort {
// For index wise sorting in descending order
public static int[] sortingnumberindexwise(int[] a, ArrayList<Integer> index) {
int k = 0;
int[] res = new int[index.size()];
int[] finalres = new int[index.size()];
for (int i = a.length - 1; i >= 0; i--) {
for (int j = 0; j < index.size(); j++) {
if (a[i] == (int) index.get(j)) {
res[k] = i;
index.remove(j);
k++;
break;
}
}
}
int g = 0;
k = 0;
for (int i = 0; i < res.length; i++) {
finalres[g] = a[res[k]];
g++;
k++;
}
return finalres;
}
public static int[] finddigitDifferenceandSort(int[] p) {
int[] finres = new int[p.length];
for (int i = 0; i < finres.length; i++) {
finres[i] = p[i];
}
// This finres array act as an temp array and reused to make final result array
int digit = 0;
ArrayList<Integer> A = new ArrayList<Integer>();
ArrayList<ArrayList<Integer>> B = new ArrayList<ArrayList<Integer>>();
for (int i = 0; i < 10; i++) {
B.add(new ArrayList<Integer>());
}
for (int i = 0; i < p.length; i++) {
int temp = 0;
temp = p[i];
while (p[i] > 0) {
digit = p[i] % 10;
p[i] /= 10;
A.add(digit);
}
int b = Collections.max(A);
int c = Collections.min(A);
int diff = b - c;
B.get(diff).add(temp);
A.clear();
}
for (int i = 0; i < B.size(); i++) {
if (B.get(i).size() > 1) {
ArrayList<Integer> C = new ArrayList<Integer>();
for (int k = 0; k < B.get(i).size(); k++) {
C.add(B.get(i).get(k));
}
B.get(i).clear();
for (int j : sortingnumberindexwise(finres, C)) {
B.get(i).add(j);
}
} else {
continue;
}
}
int k = 0;
for (int i = 0; i < B.size(); i++) {
for (int j = 0; j < B.get(i).size(); j++) {
if (B.get(i).size() == 0)
continue;
else {
finres[k] = B.get(i).get(j);
k++;
}
}
}
return finres;
}
public static void main(String[] args) {
int[] a = { 12, 21, 1, 1, 1, 2, 2, 3 };
for (int i : finddigitDifferenceandSort(a)) {
System.out.print(i + " ");
}
}
}

Most efficient way to find the smallest index where its value minus the value of a previous index is smaller than a given x?

I have five long integers p, q, s, m and x. An array numbers[] is created by the following formula.
numbers[0] = s;
for(int i=1; i<numbers.Length;i++){
numbers[i] = (p * numbers[i-1] + q) % m;
}
The first value of numbers (numbers[0]) is s.
What is the most efficient way to find index j where i < j and |numbers[j] - numbers[i]| <= x or |numbers[j] - numbers[i]| >= m-x.
For instance, in a case where p = 3, q= 7, s= 1, m= 29 en x= 1 the array will be:
numbers[0] = 1, numbers[1] = 10, numbers[2] = 8 and numbers[3] = 2.
In this case index j would be 3, because numbers[3] - numbers[0]<=x, because x is 1.
I thought about using something such as a variant of counting sort or radix sort but I can't get anything to work.

As i < j, then you need to grant that numbers has a length of at least 2.
You could do two nested loops, the outer one ranging from j = 1 to numbers.Length - 1 (granting the possible solution to be the smallest j) to i = 0 to i < j.
Then you compare both positions according your specs. If true, return j. If it finishes both loops, then there is no solution.
Edit: Code Sample
public int GetSmallestIndex(long[] numbers, long x, long m)
{
if (numbers.Length >= 2)
{
for (int j = 1; j < numbers.Length; j++)
{
for (int i = 0; i < j; i++)
{
long diff = Math.Abs(numbers[j] - numbers[i]);
if (diff <= x || diff >= m - x)
return j;
}
}
}
return -1; //If no solution is found, return -1 as convention
}

The only way to find out if something is more efficient is to benchmark it by using the StopWatch in System.Diagnostics.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
namespace ConsoleApplication1
{
class Program
{
public static void Main()
{
var stopWatch = new Stopwatch();
stopWatch.Start();
const long x = 1;
var numbers = new long[] {3, 7, 1, 29};
var theSmallestIndex = SmallestIndex(x, numbers);
stopWatch.Stop();
Console.WriteLine("Elapsed Time: {0}", stopWatch.Elapsed);
Console.WriteLine("Smallest Index: {0}", theSmallestIndex);
Console.ReadKey();
}
public static long SmallestIndex(long x, long[] numbers)
{
var values = ValuesMinusTheValueOfPreviousIndex(x, numbers.ToList());
var smallest = values.Values.OrderBy(n => n).FirstOrDefault();
var result = values.Where(n => n.Value.Equals(smallest));
return result.FirstOrDefault().Key;
}
public static Dictionary<int, long> ValuesMinusTheValueOfPreviousIndex(long x, List<long> numbers)
{
var results = new Dictionary<int, long>();
foreach (var number in numbers)
{
var index = numbers.IndexOf(number);
var previousNumber = index > 0 ? numbers.ElementAt(index - 1) : 0;
var result = number - previousNumber;
results.Add(index, result);
}
return results;
}
}
}

EDIT: Added Math.Abs as you requested in the comments
long p = 3, q = 7, s = 1, m = 29, x = 1;
long[] numbers = new long[10];
numbers[0] = s;
for (int i = 1; i < numbers.Length; i++)
{
numbers[i] = (p * numbers[i - 1] + q) % m;
}
// Find the smallest index j in numbers, where i < j &&
// (numbers[j] - numbers[i] <= x || numbers[j] - numbers[i] >= m-x)
int smallestIndex = 0;
long comparison;
for (int j = 1; j < numbers.Length; j++)
{
for (int i = 0; i < j; i++)
{
comparison = Math.Abs(numbers[j] - numbers[i]);
if (comparison <= x || comparison >= m - x)
{
smallestIndex = j;
break;
}
}
if (smallestIndex != 0) break;
}
if (smallestIndex == 0)
{
// No result matches the conditions
}
else
{
// j is the smallest index matching the conditions
// Before using Abs, in the example j is 2, because 8 - 10 = -2, lesser than x
// Now using absolute values, In the example j is 3
}

C# program that returns morse code for numbers not working

I'm trying to make a program that: When given a 4 digit number (for example, 1001) it sums the digits of that number, for 1001 this is 1 + 0 + 0 + 1 = 2, than it finds all sequences of 6 numbers from 1 to 6 (including permutations, i.e. 1*1*1*1*1*2 is different than 2*1*1*1*1*1) whose product is that number.
The result should be printed on the console in the following format: each sequence of 6 numbers, with their Morse representation, separated with a single pipe: 1 is .---- , 2 is ..---: .----|.----|.----|.----|..---|, on a new row the next permutation: .----|.----|.----|..---|.----| and so on.
The problem is, my solution doesn't show the correct answers, not even the correct number of them.
Here's my code (and please, if possible, tell me where my mistake is, and not some one line hack solutions to the problem with LINQ and regex and God knows what):
string n = Console.ReadLine();
string[] digitsChar = new string[n.Length];
for (int i = 0; i < 4; i++)
{
digitsChar[i] = n[i].ToString();
}
int[] digits = new int[digitsChar.Length];
for (int i = 0; i < 4; i++)
{
digits[i] = Convert.ToInt32(digitsChar[i]);
}
int morseProduct = digits.Sum();
Console.WriteLine(morseProduct);
List<int> morseCodeNumbers = new List<int>();
for (int i = 1; i < 6; i++)
{
for (int j = 1; i < 6; i++)
{
for (int k = 1; i < 6; i++)
{
for (int l = 1; i < 6; i++)
{
for (int m = 1; i < 6; i++)
{
for (int o = 1; o < 6; o++)
{
int product = i * j * k * l * m * o;
if (product == morseProduct)
{
morseCodeNumbers.Add(i);
morseCodeNumbers.Add(j);
morseCodeNumbers.Add(k);
morseCodeNumbers.Add(l);
morseCodeNumbers.Add(m);
morseCodeNumbers.Add(o);
}
}
}
}
}
}
}
int numberOfNumbers = morseCodeNumbers.Count;
string[] morseCodes = new string[] { "-----", ".----", "..---", "...--", "....-", "....." };
for (int i = 0; i < numberOfNumbers; i++)
{
int counter = 0;
if (i % 5 == 0)
{
Console.WriteLine();
counter = 0;
}
if (counter < 5)
{
int index = morseCodeNumbers[i];
Console.Write(morseCodes[index] + "|");
counter++;
}

A lot of your for-loop conditions refer to i instead of j,k,l and m. The same for the increment part. For example:
for (int j = 1; i < 6; i++)
should be
for (int j = 1; j < 6; j++)
Furthermore if the range is from 1 to 6 you need to change < to <=, see:
for (int i = 1; i <= 6; i++)
You don't need to convert the string to a string array to get the int array of digits btw, so while this is correct:
for (int i = 0; i < 4; i++)
{
digitsChar[i] = n[i].ToString();
}
int[] digits = new int[digitsChar.Length];
for (int i = 0; i < 4; i++)
{
digits[i] = Convert.ToInt32(digitsChar[i]);
}
you could it do like that (sry for LINQ):
var digits = n.Select(c=>(int)char.GetNumericValue(c) ).ToArray();

Creating a 3x3 Matrix and ordering numbers in a vortex from smaller to bigger

i would like to create a 3x3 matrix with input numbers and then orders number from smaller to bigger and place it in the matrix like a vortex like : 1,2,3,4,5,6,7,8,9 and place number 1 to 0.0 position,2 to 0.1, 3 to 0.2, 4 to 1.2, 5 to 2.2, 6 to 2.1, 7 to 2.0, 8 to 1.0 and 9 to 1.1.
const int MATRIX_ROWS = 3;
const int MATRIX_COLUMNS = 3;
List<int> l = new List<int>(l);
double[,] matrix = new double[MATRIX_ROWS, MATRIX_COLUMNS];
for (int i = 0; i < MATRIX_ROWS * MATRIX_COLUMNS; ++i)
{
int input;
Console.Write("Enter value");
while (!int.TryParse(Console.ReadLine(), out input))
{
Console.Write("Enter correct value!");
}
l.Add(input);
}
l.Sort();
for (int i = 0; i < MATRIX_ROWS; i++)
{
for (int j = 0; j < MATRIX_COLUMNS; j++)
{
matrix[i, j] = l[i * 3 + j];
}
I start like that to get input numbers and i would like help for the second part.

this will present you with the "vortex like" result for the matrix:
List<int> nums = new List<int>();
double[,] matrix = new double[3,3];
for (int i = 0; i < 9; ++i)
{
double input;
Console.Write("Enter value");
while (!double.TryParse(Console.ReadLine(), out input))
{
Console.Write("Enter correct value!");
}
nums.Add(int.Parse(input.ToString()));
}
nums.Sort();
int block = 0;
int[] order = new int[] { 0, 1, 2, 2, 2, 1, 0, 0, 1 };
for (int i = 0 ; i < order.Length; i++)
{
switch (block)
{
case 0:
matrix[block, order[i]] = nums[i];
if (i == 2)
block = 1;
break;
case 1:
if (i < order.Length - 3)
{
matrix[block, order[i]] = nums[i];
block = 2;
}
else
matrix[block, order[i]] = nums[i];
break;
case 2:
if(i == order.Length - 3)
{
matrix[block, order[i]] = nums[i];
block = 1;
}
else
matrix[block, order[i]] = nums[i];
break;
}
}
Console.WriteLine("The Resulting Matrix is:");
for (int row = 0, col = 0; row < 3; row++)
{
Console.WriteLine("row " + row + ": {0} - {1} - {2}", matrix[row, col], matrix[row, col + 1], matrix[row, col + 2]);
col = 0;
}
EDIT:now it displays the results.

As I see it - you can declare a List<int> l somewhere at the beginning, read the whole data by l.Add(x); then perform l.Sort() and after the data is sorted - populate your matrix. Let me know if you have further questions.
So you will get something like
const int MATRIX_ROWS = 3;
const int MATRIX_COLUMNS = 3;
List<int> l = new List<int>();
double[,] matrix = new double[MATRIX_ROWS, MATRIX_COLUMNS];
for (int i = 0; i < MATRIX_ROWS * MATRIX_COLUMNS; ++i)
{
double input;
Console.Write("Enter value");
while (!double.TryParse(Console.ReadLine(), out input))
{
Console.Write("Enter correct value!");
}
l.Add(input);
}
l.Sort();
for (int i = 0; i < MATRIX_ROWS; i++)
{
for (int j = 0; j < MATRIX_COLUMNS; j++)
{
matrix[i, j] = l[i*3 + j];
}
}

create asterisk tree with C#

Hello everyone
I try to solve asterisk tree problem
and found my code is not work correctly and can be improved.
This is output that expected
input : 5
*
* * *
* * * * *
* * *
*
input : 4
* * * *
* *
* * * *
and this is my code
static void Main(string[] args)
{
Console.Write("input:");
char input = Console.ReadKey().KeyChar;
if (char.IsDigit(input))
{
int couter = (int)char.GetNumericValue(input);
Console.WriteLine();
if (couter % 2 != 0)
{
for (int i = 1; i <= couter; i++)
{
for (int j = 3; j > i; j--)
{
Console.Write(" ");
}
for (int k = 1; k <= i; k++)
{
Console.Write(" *");
}
Console.WriteLine();
}
for (int i = couter - 1; i >= 3; i--)
{
for (int j = 1; j <= i; j++)
{
if (j <= couter - i)
{
Console.Write(" ");
}
else
{
Console.Write("* ");
}
}
Console.WriteLine();
}
}
else
{
for (int i = couter; i > 3; i--)
{
for (int j = 1; j <= i; j++)
{
if (couter - i >= j)
{
Console.Write(" ");
}
else
{
Console.Write("* ");
}
}
Console.WriteLine();
}
for (int i = couter - 1; i <= couter; i++)
{
for (int j = 0; j < i; j++)
{
Console.Write("* ");
}
Console.WriteLine();
}
}
}
}
Please could you help me to solve this problem.
Lately, I think I'm poor at algorithms and a little complex problem. Is anybody know useful link or how I can improve this skill, please let me know.
Thanks,

Check this page for input 5 (diamond) : http://www.dreamincode.net/forums/topic/126715-diamond-asterisk/
I've translated it to C# - now it displays diamonds with size that you set in variable 'rows':
int rows = 5;
StringBuilder sb = new StringBuilder();
// top part
for (int i = 1; i <= rows; i++)
{
for (int j = 1; j <= rows - i; j++)
sb.Append(' ');
for (int k = 1; k <= 2 * i - 1; k++)
sb.Append('*');
sb.AppendLine();
}
//bottom part
for (int n = rows - 1; n > 0; n--)
{
for (int l = 1; l <= rows - n; l++)
sb.Append(' ');
for (int m = 1; m <= 2 * n - 1; m++)
sb.Append('*');
sb.AppendLine();
}
Console.Write(sb.ToString());

I was initially reluctant to post it because it definitely smells like homework...
Anyway, here's a piece of working code:
static void Main(string[] args)
{
Console.Write("input:");
char input = Console.ReadKey().KeyChar;
if (char.IsDigit(input))
{
int couter = (int)char.GetNumericValue(input);
Console.WriteLine();
if (couter % 2 != 0)
PrintDiamond(couter);
else
PrintHourGlass(couter);
}
Console.ReadLine();
}
private static void PrintDiamond(int couter)
{
bool moreAsterisks = true;
for (int row = 0; row < couter; row++)
{
int nAsterisks = moreAsterisks ? (2 * row) + 1 : 2 * (couter - row - 1) + 1;
int nSpaces = (couter - nAsterisks) / 2;
if (row == (couter - 1) / 2)
moreAsterisks = false;
for (int i = 0; i < nSpaces; i++)
Console.Write(" ");
for (int i = 0; i < nAsterisks; i++)
Console.Write("*");
for (int i = 0; i < nSpaces; i++)
Console.Write(" ");
Console.WriteLine();
}
}
private static void PrintHourGlass(int couter)
{
bool moreAsterisks = false;
for (int row = 0; row < couter - 1; row++)
{
int nAsterisks = moreAsterisks ? couter - 2 * (couter - row - 2) : couter - (2 * row);
int nSpaces = (couter - nAsterisks) / 2;
if (row == (couter - 2) / 2)
moreAsterisks = true;
for (int i = 0; i < nSpaces; i++)
Console.Write(" ");
for (int i = 0; i < nAsterisks; i++)
Console.Write("*");
for (int i = 0; i < nSpaces; i++)
Console.Write(" ");
Console.WriteLine();
}
}
P.S.:
it works with any number, not just 4-5...

Here's a minified LINQ solution for your problem:
class Program
{
static void Main(string[] args)
{
Console.Write("input: ");
string line = Console.ReadLine();
int n;
if (!int.TryParse(line, out n))
{
Console.WriteLine("Enter a valid integer number.");
return;
}
for (int i = 0; i < n; i++)
{
int l = Math.Abs(n - i * 2 - 1) + 1;
if (n % 2 != 0) l = n - l + 1;
Console.Write(Enumerable.Repeat(" ", n - l).DefaultIfEmpty("").Aggregate((a, b) => a + b));
Console.WriteLine(Enumerable.Repeat("* ", l).DefaultIfEmpty("").Aggregate((a, b) => a + b));
}
}
}
It's pretty simple; inside the loop, first line calculates length of the i-th diamond row if input is even, second one corrects the calculation for odd input. The remaining two lines print i-th row using some LINQ tricks. If you don't like showing off with LINQ, you can replace thoose lines with regular for loops (which is probably going to be faster). Then the code would look like:
class Program
{
static void Main(string[] args)
{
Console.Write("input: ");
string line = Console.ReadLine();
int n;
if (!int.TryParse(line, out n))
{
Console.WriteLine("Enter a valid integer number.");
return;
}
for (int i = 0; i < n; i++)
{
int l = Math.Abs(n - i * 2 - 1) + 1;
if (n % 2 != 0) l = n - l + 1;
//Console.Write(Enumerable.Repeat(" ", n - l).DefaultIfEmpty("").Aggregate((a, b) => a + b));
//Console.WriteLine(Enumerable.Repeat("* ", l).DefaultIfEmpty("").Aggregate((a, b) => a + b));
for (int c = 0; c < n - l; c++) Console.Write(" ");
for (int c = 0; c < l; c++) Console.Write("* ");
Console.WriteLine();
}
}
}