#!/usr/bin/env python3

def selection_sort(arr):

    for i in range(len(arr)):
        print(i, ': ', l)

        # index of the minimum index
        minx = i

        for j in range(i+1, len(arr)):
            if arr[j] < arr[minx]:
                minx = j

        # Swap values
        tmp = arr[minx]
        arr[minx] = arr[i]
        arr[i] = tmp


array = [15, 7, 20, -5, 3, 2, 19, 18, 21]

selection_sort(array)
print(array)