[HackerRank] Sorting: Bubble Sort (Python)

Consider the following version of Bubble Sort:

for (int i = 0; i < n; i++) {
    
    for (int j = 0; j < n - 1; j++) {
        // Swap adjacent elements if they are in decreasing order
        if (a[j] > a[j + 1]) {
            swap(a[j], a[j + 1]);
        }
    }
    
}

Given an array of integers, sort the array in ascending order using the Bubble Sort algorithm above. Once sorted, print the following three lines:

1. Array is sorted in numSwaps swaps., where numSwaps is the number of swaps that took place.
2. First Element: firstElement, where firstElement is the first element in the sorted array.
3. Last Element: lastElement, where lastElement is the last element in the sorted array.

Hint: To complete this challenge, you must add a variable that keeps a running tally of all swaps that occur during execution.

For example, given a worst-case but small array to sort: a = [ 6, 4, 1 ] we go through the following steps:

swap    a       
0       [6,4,1]
1       [4,6,1]
2       [4,1,6]
3       [1,4,6]

It took 3 swaps to sort the array. Output would be

Array is sorted in 3 swaps.  
First Element: 1  
Last Element: 6 

Function Description

Complete the function countSwaps in the editor below. It should print the three lines required, then return.

countSwaps has the following parameter(s):

• a: an array of integers .

Input Format

The first line contains an integer, n, the size of the array a.
The second line contains n space-separated integers a [ i ] .

 

Constraints

• 2 <= n <= 600
• 1 <= a [ i ] <= 2 x 10^6

Output Format

You must print the following three lines of output:

1. Array is sorted in numSwaps swaps., where numSwaps is the number of swaps that took place.
2. First Element: firstElement, where firstElement is the first element in the sorted array.
3. Last Element: lastElement, where lastElement is the last element in the sorted array.

Sample Input 0

3
1 2 3

Sample Output 0

Array is sorted in 0 swaps.
First Element: 1
Last Element: 3

Explanation 0
The array is already sorted, so 0 swaps take place and we print the necessary three lines of output shown above.

 

Sample Input 1

3
3 2 1

Sample Output 1

Array is sorted in 3 swaps.
First Element: 1
Last Element: 3

Explanation 1

The array is not sorted, and its initial values are: { 3, 2, 1 }. The following 3 swaps take place:

1. { 3, 2, 1 } -> { 2, 3, 1 }
2. { 2, 3, 1 } -> { 2, 1, 3 }
3. { 2, 1, 3 } -> { 1, 2, 3 }

At this point the array is sorted and we print the necessary three lines of output shown above.

 

Solution

#!/bin/python3

import math
import os
import random
import re
import sys

# Complete the countSwaps function below.
def countSwaps(a):
    count = 0
    for i in range(len(a)):
        for j in range(len(a)-1):
            if a[j] > a[j+1]:
                temp = a[j]
                a[j] = a[j+1]
                a[j+1] = temp
                count = count + 1
    print("Array is sorted in {} swaps.".format(count))
    print("First Element: {}".format(a[0]))
    print("Last Element: {}".format(a[-1]))

Solution 풀이

버블 소트를 하면서 카운트하고 나중에 출력시 맨앞 맨뒤의 값 출력을 해주었습니다.

 

SOMJANG/CODINGTEST_PRACTICE