Algorithms Selection Sort - ashish9342/FreeCodeCamp GitHub Wiki
The selection sort algorithm sorts an array by repeatedly finding the minimum element (considering ascending order) from the unsorted part and putting it at the beginning. The algorithm maintains two subarrays in a given array.
- The subarray which is already sorted.
- Remaining subarray which is unsorted.
In every iteration of selection sort, the minimum element (considering ascending order) from the unsorted subarray is picked and moved to the sorted subarray.
arr[] = 64 25 12 22 11
# Placing the minimum element in arr[0...4] in the beginning
11 25 12 22 64
# Placing the minimum element in arr[1...4] in the beginning
11 12 25 22 64
# Placing the minimum element in arr[2...4] in the beginning
11 12 22 25 64
# Placing the minimum element in arr[3...4] in the beginning
11 12 22 25 64
void selection_sort(int array[], int n)
{
// Contains index of minimum element in unsorted subarray
int min_index;
// Move boundary of unsorted subarray
for(int i = 0; i < n-1; i++)
{
// Find the minimum element in unsorted subarray
min_index = i;
for(int j = i+1; j < n; j++)
{
// If present element is less than element at min_index
// Then change min_index to present index
if(array[j] < array[min_index])
{
min_index = j;
}
}
// Swap the element at min_index with the first element
int temp;
temp = array[min_index];
array[min_index] = array[i];
array[i] = temp;
}
}🚀 Run Code
def selection_sort(arr):
for i in range(len(arr)):
min_x = i
for j in range(i+1,len(arr)):
if arr[j] < arr[min_x]:
min_x = j
arr[min_x], arr[i] = arr[i], arr[min_x]
arr = [64, 25, 12, 22, 11]
selection_sort(arr)
print(arr) # Prints [11, 12, 22, 25, 64]🚀 Run Code
Time Complexity: O(n*n) Due to the two nested loops.