Introduction

It's not the first time to implement it, but I thought that I might have deepened my understanding a little compared to when I was a beginner, so I thought I'd write an article. I think this bubble sort, the movement is amazingly beautiful. The principle of beautiful things is not intuitive. After all, I think that the opportunity to sort by familiarity is Trump's hand, but I have never used this bubble sort in the elementary alignment. (Do you have any? Lol)

code

`bubble_sort.py`


def bubble_sort(A):
    flag = 1
    i = 0
    while flag:
        flag = 0
        for j in range(len(A)-1,i,-1):
            if A[j] < A[j-1]:
                A[j],A[j-1] = A[j-1],A[j]
                flag = 1
        i += 1
    return A

how to use

The argument is an arbitrary array and returns the sorted array.

Description

Loop variable i -The beginning of the sorted array ・ It increases by 1 from the beginning -The end condition is when sorting is completed = when there is no element exchange (expressed by flag)

Loop variable j -Used for exchanging adjacent elements in the end sort part ・ Decrease by 1 from the end to i + 1

flag ・ Used as a continuation condition for while ・ If there is an element exchange, it becomes 1 and the next loop continues.

in conclusion

I thought that i should simply use a for statement from the beginning to the end! However, in bubble sort, when a loop starts, it doesn't stop until all the loops are checked, so useless comparisons are made many times. That's right. I was happy when I understood that I would end it if there was no exchange using a variable called flag. If you like it, please follow me and it will be motivating. Thank you. !!!!!

References

-[Algorithm and data structure for programming contest capture] (https://www.amazon.co.jp/%E3%83%97%E3%83%AD%E3%82%B0%E3%83%A9%E3%83%9F%E3%83%B3%E3%82%B0%E3%82%B3%E3%83%B3%E3%83%86%E3%82%B9%E3%83%88%E6%94%BB%E7%95%A5%E3%81%AE%E3%81%9F%E3%82%81%E3%81%AE%E3%82%A2%E3%83%AB%E3%82%B4%E3%83%AA%E3%82%BA%E3%83%A0%E3%81%A8%E3%83%87%E3%83%BC%E3%82%BF%E6%A7%8B%E9%80%A0-%E6%B8%A1%E9%83%A8-%E6%9C%89%E9%9A%86/dp/4839952957)

Bubble sort