Question

Write a Program  to implement Selection sort

Answer 1

Ques . Write a Program  to implement Selection sort

Answer : Selection sort is an sorting algorithm in which the array is divided into sorted array and unsorted array and we need to find the minimum element from unsorted array  and put it in a sorted array sequence .

Algorithm : 

1. Set minimum element to index 0
2. Search the minimum element in the array
3. Swap with value at minimum index 
4. Increment minimum to point to next element
5. Repeat until list is sorted

Example : 

a = [86, 45, 6, 32, 5]

here we need to find the minimum element and place it in the beginning from i=0 to 4

5 45 6 32 86

here we need to find the minimum element and place it in the beginning from i=1 to 4

5 6 45 32 86

here we need to find the minimum element and place it in the beginning from i=2 to 4

5 6 32 45 86

here we need to find the minimum element and place it in the beginning from i=3 to 4

5 6 32 45 86

program : 

def selection_Sort(L):

   # i indicates how many items were sorted

   for i in range(len(L)-1):

        # To find the minimum value of the unsorted segment

        # We first assume that the first element is the lowest

        min_index = i

        # We then use j to loop through the remaining elements

        for j in range(i+1, len(L)-1):

            # Update the min_index if the element at j is lower than it

            if L[j] < L[min_index]:

                min_index = j

        # After finding the lowest item of the unsorted regions, swap with the first unsorted item

        L[i], L[min_index] = L[min_index], L[i]

   return L

# Driver code to test above  

L = [80, 10, 60, 40, 70, 50] 

print("Unsorted list is:",L)

# Let's see the list after we run the Selection Sort

print("Sorted list is:",selection_Sort(L))

Output : 

Unsorted list is: [80, 10, 60, 40, 70, 50] 

Sorted list is: [10, 40, 60, 70, 80, 50]

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