A guide to implementing selection sort in Python

How to use Python for selection sort

Selection sort is a simple but less efficient sorting algorithm. Its basic idea is to select the smallest (or largest) element from the data to be sorted each time and place it at the end of the sorted sequence. Repeat this process multiple times until all data is sorted.

The following will introduce in detail how to use Python for selection sorting and provide specific code examples.

1. First, define a selection sort function, named selection_sort, which accepts a list to be sorted as a parameter.

def selection_sort(lst):
    n = len(lst)
    for i in range(n-1):
        min_index = i  # 记录当前最小值的索引
        for j in range(i+1, n):
            if lst[j] < lst[min_index]:
                min_index = j
        lst[i], lst[min_index] = lst[min_index], lst[i]  # 将最小值交换到已排序序列的末尾

2. Call the selection_sort function in the main program and pass in the list to be sorted. The following is an example:

lst = [64, 25, 12, 22, 11]
selection_sort(lst)
print("排序后的列表:", lst)

The output result is:

排序后的列表: [11, 12, 22, 25, 64]

The above is a specific code example of using Python for selection sorting. The execution of the code is further explained below.

In selection sorting, we implement it through two levels of loops. The outer loop controls the starting position of selecting the smallest element from the unsorted subsequence each time, while the inner loop is used to find the smallest element in the current unsorted subsequence. By comparing the current element with the smallest element that has been selected, we can get the index of the smallest element in the subsequence.

After finding the smallest element, we swap it with the last element of the sorted sequence, so that the smallest element is placed at the end of the sorted sequence. By repeating this process, each time selecting the smallest element and placing it at the end of the sorted sequence, we end up with an ordered list.

It should be noted that the time complexity of selection sort is O(n^2), where n is the number of elements to be sorted. Although its efficiency is relatively low, selection sort is still a simple and easy-to-implement sorting algorithm when the data size is small.

I hope the above content will help you understand and use Python for selection sorting. If you have any other questions, please ask.

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