Day 20: Sorting

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Consider the following version of Bubble Sort:

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, , of size  distinct elements, sort the array in ascending order using the Bubble Sort algorithm above. Once sorted, print the following  lines:

1. Array is sorted in numSwaps swaps. 
   where  is the number of swaps that took place.
2. First Element: firstElement 
   where  is the first element in the sorted array.
3. Last Element: lastElement 
   where  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, , denoting the number of elements in array . 
The second line contains  space-separated integers describing the respective values of .

Constraints

• , where .

Output Format

Print the following three lines of output:

1. Array is sorted in numSwaps swaps. 
   where  is the number of swaps that took place.
2. First Element: firstElement 
   where  is the first element in the sorted array.
3. Last Element: lastElement 
   where  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  swaps take place and we print the necessary  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, so we perform the following  swaps:

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

풀이

중간에 전부 sort 된게 맞으면 break 하는게 더 좋은 로직일 듯 하다

난 numberOfSwaps 하나만 넣었는데 체크용으로 int 하나 더 있는게 좋을 듯

package Day20;

import java.util.Scanner;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] a = new int[n];
        for (int a_i = 0; a_i < n; a_i++) {
            a[a_i] = in.nextInt();
        }
        // Write Your Code Here
        Sorting sorting = new Sorting(a);
        int swapCount = sorting.bubbleSorting();
        System.out.println("Array is sorted in " + String.valueOf(swapCount) +" swaps.");
        System.out.println("First Element: " + sorting.getFirstElement());
        System.out.println("Last Element: " + sorting.getLastElement());
    }
}

class Sorting {

    private int[] array;

    Sorting(int[] array) {
        this.array = array;
    }

    Integer bubbleSorting() {
        int numberOfSwaps = 0;
        for (int i = 0; i < array.length; i++) {
            // Track number of elements swapped during a single array traversal

            for (int j = 0; j < array.length - 1; j++) {
                // Swap adjacent elements if they are in decreasing order
                if (array[j] > array[j + 1]) {
                    int temp = array[j];
                    array[j] = array[j+1];
                    array[j+1] = temp;
                    numberOfSwaps++;
                }
            }

            // If no elements were swapped during a traversal, array is sorted
            if (numberOfSwaps == 0) {
                break;
            }
        }
        return numberOfSwaps;
    }

    Integer getFirstElement() {
        return array[0];
    }

    Integer getLastElement() {
        return array[array.length - 1];
    }
}