Develop Reference

Is there a way to throw an exception when string is typed in an arrayc#?

I am new in this fascinating world of programming. I have done this array, but when I type a non integer it crashes. I have tried many ways like int.Parse(console.readLine)), tryparse(text, out int) and ConvertTo32 ,However it continues saying that "Input string was not in correct format." Thanks
using System;
namespace BubbleSort
{
class Program
{
public static void HelpME(int[] a, int t)
{
for (int j = 0; j <= a.Length - 2; j++)
{
for (int i = 0; i <= a.Length - 2; i++)
{
if (a[i] > a[i + 1])
{
t = a[i + 1];
a[i + 1] = a[i];
a[i] = t;
}
}
}
}
static void Main(string[] args)
{
int[] num = { 1, 2, 3, 4, 5 };
int[] a = new int[5];
for (int x = 0; x < 5; x++)
{
Console.WriteLine($"Input enter {num[0 + x]} of five");
a[0 + x] = Convert.ToInt32(Console.ReadLine());
}
Console.WriteLine("The Array is : ");
for (int i = 0; i < a.Length; i++)
{
Console.WriteLine(a[i]);
}
{
HelpME(num, 5);
}
Console.WriteLine("The Sorted Array :");
foreach (int aray in a)
{
Console.Write(aray + " ");
}
Console.ReadLine();
}
}
}

you should validate the user unput by using int.TryParse method. If the entered string can be converted to int then only it should be inserted into the array, otherwise the program should ignore that value.
static void Main(string[] args)
{
int[] num = { 1, 2, 3, 4, 5 };
int[] a = new int[5];
for (int x = 0; x < 5; x++)
{
Console.WriteLine($"Input enter {num[0 + x]} of five");
int temp = 0;
string input = Console.ReadLine();
if(int.TryParse(input, out temp))
{
a[0 + x] = Convert.ToInt32(input);
}
}
Console.WriteLine("The Array is : ");
for (int i = 0; i < a.Length; i++)
{
Console.WriteLine(a[i]);
}
{
HelpME(num, 5);
}
Console.WriteLine("The Sorted Array :");
foreach (int aray in a)
{
Console.Write(aray + " ");
}
Console.ReadLine();
}

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 + " ");
}
}
}

Find ascending duplicate pairs in an array

Given an array A with zero index and N integers find equal elements with different positions in the array. Pair of indexes (P,Q) such that 0 <= P < Q < N such that A[P] = A[Q]. My algorithm is below but I am looking for a O(N*logN) solution.
public int solution(int[] A)
{
int N = A.Length;
int count = 0;
for (int j = 0; j < N; j++)
{
count += FindPairs(A[j], j, A);
}
return count;
}
public int FindPairs(int item, int ci, int[] A)
{
int len = A.Length;
int counter=0;
int k = ci+1;
while (k < len)
{
if (item == A[k])
counter++;
k++;
}
return counter;
}

From your code, it looks like the goal is to return the count of ascending duplicate pairs in A.
We observe that if there are m occurrences of the number x in A, then the number of ascending duplicate pairs of the value x is m choose 2, or m (m - 1) / 2.
So, we sum up m (m - 1) / 2 for each unique x, giving us the answer.
In pseudocode, this looks like:
count = new Dictionary();
foreach a in A {
count[a]++;
}
total = 0;
foreach key, value in count {
total += value * (value - 1) / 2;
}
return total;
This algorithm is O(N).

Recent interview question … here is what I did:
using System;
using System.Collections.Generic;
using System.Linq;
namespace Codility
{
internal class Program
{
public struct Indice
{
public Indice(int p, int q)
{
P = p;
Q = q;
}
public int P;
public int Q;
public override string ToString()
{
return string.Format("({0}, {1})", P, Q);
}
}
private static void Main(string[] args)
{
// 0 1 2 3 4 5
int[] list = new int[] {3,3,3,3,3,3};
int answer = GetPairCount(list);
Console.WriteLine("answer = " + answer);
Console.ReadLine();
}
private static int GetPairCount(int[] A)
{
if (A.Length < 2) return 0;
Dictionary<int, Dictionary<Indice, Indice>> tracker = new Dictionary<int, Dictionary<Indice, Indice>>();
for (int i = 0; i < A.Length; i++)
{
int val = A[i];
if (!tracker.ContainsKey(val))
{
Dictionary<Indice, Indice> list = new Dictionary<Indice, Indice>();
Indice seed = new Indice(i, -1);
list.Add(seed, seed);
tracker.Add(val, list);
}
else
{
Dictionary<Indice, Indice> list = tracker[val];
foreach (KeyValuePair<Indice,Indice> item in list.ToList())
{
Indice left = new Indice(item.Value.P, i);
Indice right = new Indice(i, item.Value.Q);
if (!list.ContainsKey(left))
{
list.Add(left, left);
Console.WriteLine("left= " + left);
}
if (!list.ContainsKey(right))
{
list.Add(right, right);
Console.WriteLine("\t\tright= " + right);
}
}
}
}
return tracker.SelectMany(kvp => kvp.Value).Count(num => num.Value.Q > num.Value.P);
}
}
}

I think this is best version I got in c#.
static void Main(string[] args)
{
var a = new int[6] { 3, 5, 6, 3, 3, 5 };
//Push the indices into an array:
int[] indices = new int[a.Count()];
for (int p = 0; p < a.Count(); ++p) indices[p] = p;
//Sort the indices according to the value of the corresponding element in a:
Array.Sort(indices, (k, l) =>Compare(a[k], a[l]));
//Then just pull out blocks of indices with equal corresponding elements from indices:
int count = 0;
int i = 0;
while (i < indices.Count())
{
int start = i;
while (i < indices.Count() && a[indices[i]] == a[indices[start]])
{
++i;
}
int thisCount = i - start;
int numPairs = thisCount * (thisCount - 1) / 2;
count += numPairs;
}
Console.WriteLine(count);
Console.ReadKey();
}
//Compare function to return interger
private static int Compare(int v1, int v2)
{
if (v2 > v1)
return 1;
if (v1 == v2)
return 0;
else
return -1;
}
This approach has O(n log n) complexity overall, because of the sorting. The counting of the groups is linear.

Try this:
private static int GetIdenticalPairCount(int[] input)
{
int identicalPairCount = 0;
Dictionary<int, int> identicalCountMap = new Dictionary<int, int>();
foreach (int i in input)
{
if (identicalCountMap.ContainsKey(i))
{
identicalCountMap[i] = identicalCountMap[i] + 1;
if (identicalCountMap[i] > 1)
{
identicalPairCount += identicalCountMap[i];
}
else
{
identicalPairCount++;
}
}
else
{
identicalCountMap.Add(i, 0);
}
}
return identicalPairCount;
}

Test my version:
public int solution(int[] A)
{
int N = A.Length;
int count = 0;
for (int j = 0; j < N - 1; j++)
for (int i = j + 1; i < N; i++)
if (A[i] == A[j])
count++;
return count;
}

Implementing quicksort algorithm

I found quicksort algorithm from this book
This is the algorithm
QUICKSORT (A, p, r)
if p < r
q = PARTITION(A, p, r)
QUICKSORT(A, p, q-1)
QUICKSORT(A, q+1, r)
PARTITION(A, p, r)
x=A[r]
i=p-1
for j = p to r - 1
if A <= x
i = i + 1
exchange A[i] with A[j]
exchange A[i+1] with A[r]
return i + 1
And I made this c# code:
private void quicksort(int[] input, int low, int high)
{
int pivot_loc = 0;
if (low < high)
pivot_loc = partition(input, low, high);
quicksort(input, low, pivot_loc - 1);
quicksort(input, pivot_loc + 1, high);
}
private int partition(int[] input, int low, int high)
{
int pivot = input[high];
int i = low - 1;
for (int j = low; j < high-1; j++)
{
if (input[j] <= pivot)
{
i++;
swap(input, i, j);
}
}
swap(input, i + 1, high);
return i + 1;
}
private void swap(int[] ar, int a, int b)
{
temp = ar[a];
ar[a] = ar[b];
ar[b] = temp;
}
private void print(int[] output, TextBox tbOutput)
{
tbOutput.Clear();
for (int a = 0; a < output.Length; a++)
{
tbOutput.Text += output[a] + " ";
}
}
When I call function like this quicksort(arr,0,arr.Length-1); I get this error An unhandled exception of type 'System.StackOverflowException' occurred it pass empty array... when call function like this quicksort(arr,0,arr.Length); I get error Index was outside the bounds of the array. on this line int pivot = input[high]; but array passed successfully.
I also want to print it like this print(input,tbQuick); but where to place it so it would print when quicksort finished?

You did not properly implement the base case termination, which causes quicksort to never stop recursing into itself with sublists of length 0.
Change this:
if (low < high)
pivot_loc = partition(input, low, high);
quicksort(input, low, pivot_loc - 1);
quicksort(input, pivot_loc + 1, high);
to this:
if (low < high) {
pivot_loc = partition(input, low, high);
quicksort(input, low, pivot_loc - 1);
quicksort(input, pivot_loc + 1, high);
}

In addition to Deestan's answer, you also have this wrong:
for (int j = low; j < high-1; j++)
It should be:
for (int j = low; j < high; j++)

Just in case you want some shorter code for Quicksort:
IEnumerable<int> QuickSort(IEnumerable<int> i)
{
if (!i.Any())
return i;
var p = (i.First() + i.Last) / 2 //whichever pivot method you choose
return QuickSort(i.Where(x => x < p)).Concat(i.Where(x => x == p).Concat(QuickSort(i.Where(x => x > p))));
}
Get p (pivot) with whatever method is suitable of course.

This is the shortest implementation of Quick Sort algorithm (Without StackOverflowException)
IEnumerable<T> QuickSort<T>(IEnumerable<T> i) where T :IComparable
{
if (!i.Any()) return i;
var p = i.ElementAt(new Random().Next(0, i.Count() - 1));
return QuickSort(i.Where(x => x.CompareTo(p) < 0)).Concat(i.Where(x => x.CompareTo(p) == 0)).Concat(QuickSort(i.Where(x => x.CompareTo(p) > 0)));
}

A Simple Quick Sort Implementation.
https://github.com/bharathkumarms/AlgorithmsMadeEasy/blob/master/AlgorithmsMadeEasy/QuickSort.cs
using System;
using System.Collections.Generic;
using System.Linq;
namespace AlgorithmsMadeEasy
{
class QuickSort
{
public void QuickSortMethod()
{
var input = System.Console.ReadLine();
string[] sInput = input.Split(' ');
int[] iInput = Array.ConvertAll(sInput, int.Parse);
QuickSortNow(iInput, 0, iInput.Length - 1);
for (int i = 0; i < iInput.Length; i++)
{
Console.Write(iInput[i] + " ");
}
Console.ReadLine();
}
public static void QuickSortNow(int[] iInput, int start, int end)
{
if (start < end)
{
int pivot = Partition(iInput, start, end);
QuickSortNow(iInput, start, pivot - 1);
QuickSortNow(iInput, pivot + 1, end);
}
}
public static int Partition(int[] iInput, int start, int end)
{
int pivot = iInput[end];
int pIndex = start;
for (int i = start; i < end; i++)
{
if (iInput[i] <= pivot)
{
int temp = iInput[i];
iInput[i] = iInput[pIndex];
iInput[pIndex] = temp;
pIndex++;
}
}
int anotherTemp = iInput[pIndex];
iInput[pIndex] = iInput[end];
iInput[end] = anotherTemp;
return pIndex;
}
}
}
/*
Sample Input:
6 5 3 2 8
Calling Code:
QuickSort qs = new QuickSort();
qs.QuickSortMethod();
*/

Code Implemented with Iteration With last element as Pivot
<code>https://jsfiddle.net/zishanshaikh/5zxvwoq0/3/ </code>
function quickSort(arr,l,u) {
if(l>=u)
{
return;
}
var pivot=arr[u];
var pivotCounter=l;
for(let i=l;i<u;i++)
{
if(arr[i] <pivot )
{
var temp= arr[pivotCounter];
arr[pivotCounter]=arr[i] ;
arr[i]=temp;
pivotCounter++;
}
}
var temp2= arr[pivotCounter];
arr[pivotCounter]=arr[u] ;
arr[u]=temp2;
quickSort(arr,pivotCounter+1,u);
quickSort(arr,0,pivotCounter-1);
}
<code>https://jsfiddle.net/zishanshaikh/exL9cdoe/1/</code>
Code With first element as Pivot
//Logic For Quick Sort
function quickSort(arr,l,u) {
if(l>=u)
{
return;
}
var pivot=arr[l];
var pivotCounter=l+1;
for(let i=l+1;i<u;i++)
{
if(arr[i] <pivot )
{
var temp= arr[pivotCounter];
arr[pivotCounter]=arr[i] ;
arr[i]=temp;
pivotCounter++;
}
}
var j=pivotCounter-1;
var k=l+1;
while(k<=j)
{
var temp2= arr[k-1];
arr[k-1]=arr[k] ;
arr[k]=temp2;
k++;
}
arr[pivotCounter-1]=pivot;
quickSort(arr,pivotCounter,u);
quickSort(arr,0,pivotCounter-2);
}

A simple generic C# implementation of QuickSort, can use first or last value or any other intermediate value for pivot
using System;
namespace QuickSort
{
class Program
{
static void Main(string[] args)
{
int[] arInt = { 6, 4, 2, 8, 4, 5, 4, 5, 4, 5, 4, 8, 11, 1, 7, 4, 13, 5, 45, -1, 0, -7, 56, 10, 57, 56, 57, 56 };
GenericQuickSort<int>.QuickSort(arInt, 0, arInt.Length - 1);
string[] arStr = { "Here", "Is", "A", "Cat", "Really", "Fast", "And", "Clever" };
GenericQuickSort<string>.QuickSort(arStr, 0, arStr.Length - 1); ;
Console.WriteLine(String.Join(',', arInt));
Console.WriteLine(String.Join(',', arStr));
Console.ReadLine();
}
}
class GenericQuickSort<T> where T : IComparable
{
public static void QuickSort(T[] ar, int lBound, int uBound)
{
if (lBound < uBound)
{
var loc = Partition(ar, lBound, uBound);
QuickSort(ar, lBound, loc - 1);
QuickSort(ar, loc + 1, uBound);
}
}
private static int Partition(T[] ar, int lBound, int uBound)
{
var start = lBound;
var end = uBound;
var pivot = ar[uBound];
// switch to first value as pivot
// var pivot = ar[lBound];
while (start < end)
{
while (ar[start].CompareTo(pivot) < 0)
{
start++;
}
while (ar[end].CompareTo(pivot) > 0)
{
end--;
}
if (start < end)
{
if (ar[start].CompareTo(ar[end]) == 0)
{
start++;
}
else
{
swap(ar, start, end);
}
}
}
return end;
}
private static void swap(T[] ar, int i, int j)
{
var temp = ar[i];
ar[i] = ar[j];
ar[j] = temp;
}
}
}
Output:
-7,-1,0,1,2,4,4,4,4,4,4,5,5,5,5,6,7,8,8,10,11,13,45,56,56,56,57,57
A,And,Cat,Clever,Fast,Here,Is,Really
One important thing to notice here is that this optimized and simple code properly handles duplicates. I tried several posted quick sort code. Those do not give correct result for this (integer array) input or just hangs, such as https://www.w3resource.com/csharp-exercises/searching-and-sorting-algorithm/searching-and-sorting-algorithm-exercise-9.php and http://www.softwareandfinance.com/CSharp/QuickSort_Iterative.html. Therefore, if author also wants to use the code which handles duplicates this would be a good reference.

C# heapSort ,System.Timers; to check algorithm time

I have to check HeapSort algorithm time in C# , my problem is that I Know I must use System.Timers , because I don't know how to measures the algorithm time.
I have to check the algorithm time for table contains 1000 ,10 000 , 100 000 and 1000 000 integers.
Help me good people please.
This is the code:
using System;
namespace Sort
{
class Program
{
public static void Adjust(int[] list, int i, int m)
{
int Temp = list[i];
int j = i * 2 + 1;
while (j <= m)
{
if (j < m)
if (list[j] < list[j + 1])
j = j + 1;
if (Temp < list[j])
{
list[i] = list[j];
i = j;
j = 2 * i + 1;
}
else
{
j = m + 1;
}
}
list[i] = Temp;
}
public static void HeapSort(int[] list)
{
int i;
//Boulding a heap
for (i = (list.Length - 1) / 2; i >= 0; i--)
Adjust(list, i, list.Length - 1);
for (i = list.Length - 1; i >= 1; i--)
{
int Temp = list[0];
list[0] = list[i];
list[i] = Temp;
Adjust(list, 0, i - 1);
}
}
static void Main(string[] args)
{
Console.Title = "HeapSort";
int i;
int[] a = { 12, 3, -12, 27, 34, 23, 1, 81, 45,
17, 9, 23, 11, 4, 121 };
Console.WriteLine("Data before sort ");
for (i = 0; i < a.Length; i++)
Console.Write(" {0} ", a[i]);
Console.WriteLine();
HeapSort(a);
Console.WriteLine("Data after sort");
for (i = 0; i < a.Length; i++)
Console.Write(" {0} ", a[i]);
Console.ReadLine();
}
}
}
I've write this with You help , does is good ?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
namespace Sort
{
class Program
{
public static void Adjust(int[] list, int i, int m)
{
int Temp = list[i];
int j = i * 2 + 1;
while (j <= m)
{
if (j < m)
if (list[j] < list[j + 1])
j = j + 1;
if (Temp < list[j])
{
list[i] = list[j];
i = j;
j = 2 * i + 1;
}
else
{
j = m + 1;
}
}
list[i] = Temp;
}
public static void HeapSort (int[] list)
{
int i;
//Boulding a heap
for (i = (list.Length - 1) / 2;i >=0;i--)
Adjust (list, i, list.Length - 1);
for ( i = list.Length - 1; i >= 1; i--)
{
int Temp = list [0];
list [0] = list [i];
list [i] = Temp;
Adjust (list, 0, i - 1);
}
}
static void Main(string[] args)
{
Console.Title = "HeapSort";
int i;
Random myRandom = new Random();//Creating instance of class Random
Stopwatch myTime = new Stopwatch(); //variable for time measurement
int[] a = new int[1000]; //table contents 1000 variables
for (i = 0; i < a.Length; i++)
a[i] = myRandom.Next(100);
Console.WriteLine("Data before sort ");
for (i = 0; i < a.Length; i++)
Console.Write(" {0} ", a[i]);
Console.WriteLine();
myTime.Start();
HeapSort(a);
myTime.Stop();
string TimeEl = myTime.Elapsed.ToString();
Console.WriteLine("Data after sort");
for (i = 0; i < a.Length; i++)
Console.Write(" {0} ", a[i]);
Console.WriteLine();
Console.WriteLine();
Console.WriteLine("time elapsed: {0} ", TimeEl);
Console.ReadLine();
}
}
}

If you're looking for time measurements, use the Stopwatch class.
This allows you to easily measure some time using the Start() and Stop() method. The Elapsed property will then tell you how long the operation took.

You could use the Stopwatch class to measure time:
var watch = Stopwatch.StartNew();
SomeFunctionThatCallsYourAlgorithm();
watch.Stop();
Console.WriteLine("algorithm execution time: {0}ms", watch.ElapsedMilliseconds);

There's some code from Vance Morrison's weblog that uses the Stopwatch class (as described above), but does multiple runs and performs some statistical analysis to give you the mean, median runtime, along with the standard derivation.
Check it out here:
Link