So I’m trying to implement selection sort in C# but the output isn’t exactly what I’m expecting,
I tried tracing the loops and even brought out the good ol pen and paper but to no avail
using System;
namespace App
{
class Application
{
public static void Main(string[] args)
{
int[] arr = {23,45,76,22,5666,845,11,2};
foreach (int i in sort(arr))
{
Console.WriteLine($"{i}");
}
}
public static int[] sort(int[] arr)
{
int ind = 0;
int minInd = 0;
int jInd = 0;
foreach(int i in arr)
{
int min = i;
minInd = ind;
foreach(int j in arr)
{
if (i == j)
{
}
else
{
if (j < min)
{
min = j;
minInd = jInd;
}
}
jInd++;
}
int temp = i;
arr[ind] = arr[minInd];
arr[minInd] = temp;
ind++;
jInd = 0;
}
return arr;
}
}
}
for some info, minInd is the index of the minimum value, ind is the index of the outer loop iteraion, and jInd is the index for the inner loop itteration, i tried using the built in IndexOf from the array class but that just results in an indexoutofbounds error, could be a problem in the way C# handles array, i normally use java so maybe they handle them in different ways, also I understand that the time complexity of this algorithm is n^2 so why do we still use it.
The output is 45
76
22
5666
845
11
23
2
>Solution :
You’re doing your swapping outside of the inner loop instead of within. You don’t really need to iterate through every element of the array in your inner loop either (see my edits to your solution below).
Speaking of looping, don’t use for-each in a case like this; use plain old for. In the case of Selection Sort it’s also easier to count down the array which is expressed more clearly using a for loop. A for loop, moreover, obviates the need for many of these additional variable declarations you have.
Finally, it’s generally considered bad practice to have an if with no body. If the if condition executes no code when true, check the boolean not instead and execute the code in your else block. This also eliminates the extra check of (i == j) you have which is frankly superfluous.
For learning purposes I’ve adapted your code to an improved implementation (though not necessarily the ideal one):
static int[] sort(int[] arr)
{
//int ind = 0;
//int minInd = 0;
//int jInd = 0;
for (int i = arr.Length - 1; i > 0; i--)
{
//int min = i;
//minInd = ind;
for (int j = 0; j < i; j++)
{
if (arr[j + 1] < arr[j])
{
int min = arr[j + 1];
arr[j + 1] = arr[j];
arr[j] = min;
}
//else
//{
// if (j < min)
// {
// min = j;
// minInd = jInd;
// }
//}
//jInd++;
}
//int temp = i;
//arr[ind] = arr[minInd];
//arr[minInd] = temp;
//ind++;
//jInd = 0;
}
return arr;
}