## Thursday, May 5, 2022

### Question 79 : Write an algorithm to implement selection sort sort?

Selection sort is an in-place comparison sorting algorithm. It is very simple to implement but it does not go well with a large number of inputs.

## Selection sort algorithm

• Find the minimum element in the list.
• Swap minimum element with current element.
• Repeat the whole process until array is fully sorted.
Below visualization will make it more clear

## Selection sort algorithm

``````Import java.util.Arrays;
public class SelectionSortMain {

public static int[] selectionSort(int[] arr) {

for (int i = 0; i < arr.length - 1; i++) {
int index = i;
for (int j = i + 1; j < arr.length; j++)
if (arr[j] < arr[index])
index = j;

int smallerNumber = arr[index];
arr[index] = arr[i];
arr[i] = smallerNumber;
}
return arr;
}

public static void main(String a[]) {

int[] arr = {
40,
10,
-30,
45,
39,
32
};
System.out.println("Before Sorting : ");
System.out.println(Arrays.toString(arr));
arr = selectionSort(arr);
System.out.println("===================");
System.out.println("After Sorting : ");
System.out.println(Arrays.toString(arr));
}
}
}
}``````
When you run above program, you will get below output:
``````Before Sorting :
[40, 10, -30, 45, 39, 32]
===================
After Sorting :
[-30, 10, 32, 39, 40, 45]Time complexity
Best case : O(N^2)
Average case : O(N^2)
Worst case : O(N^2)``````
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