Day 20: Sorting

Objective

Today, we’re discussing a simple sorting algorithm called Bubble Sort. Check out the Tutorial tab for learning materials and an instructional video!

Consider the following version of Bubble Sort:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

for (int i = 0; i < n; i++) {
    // Track number of elements swapped during a single array traversal
    int numberOfSwaps = 0;
    
    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]);
            numberOfSwaps++;
        }
    }
    
    // If no elements were swapped during a traversal, array is sorted
    if (numberOfSwaps == 0) {
        break;
    }
}

Task

Given an array, a, of size n distinct elements, sort the array in ascending order using the Bubble Sort algorithm above. Once sorted, print the following 3 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 will need to add a variable that keeps a running tally of all swaps that occur during execution.

Input Format

The first line contains an integer, n, denoting the number of elements in array a. The second line contains n space-separated integers describing the respective values of a₀, a₁, …, a_n-1.

Constraints

• 2 <= n <= 600
• 1 <= a_i <= 2 X 10⁶, where 0 <= i < n

Output Format

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 lastElements is the last element in the sorted array.

Sample Input 0

1
2

3
1 2 3

Sample Output 0

1
2
3

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 3 lines of output shown above.

Sample Input 1

1
2

3
3 2 1

Sample Output 1

1
2
3

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

Explanation 1

The array a = [3, 2, 1] is not sorted, so we perform the following swaps:

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 3 lines of output shown above.

Solution

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33

function main() {
    var n = parseInt(readLine());
    a = readLine().split(' ');
    a = a.map(Number);
    // Write Your Code Here
    let numberOfSwaps = 0;

    const bubbleSort = (values) => {
        let swapped;

        do {
            swapped = false;
            
            for (let i = 0, { length } = values; i < length; i++) {
                if (values[i] > values[i + 1]) {
                    let tmp = values[i];
                    
                    values[i] = values[i + 1];
                    values[i + 1] = tmp;
                    
                    swapped = true;
                    numberOfSwaps++;
                }
            }
        } while (swapped);

        return values;
    };

    let result = bubbleSort(a);

    console.log(`Array is sorted in ${numberOfSwaps} swaps.\nFirst Element: ${result[0]}\nLast Element: ${result[n - 1]}`);
}