BubbleSort

```java
import java.util.Arrays;

public class BubbleSort {

public static void bubbleSort(int[] arr) {

    int count = 0;
    System.out.println("Before BubbleSort");
    Arrays.stream(arr).forEach(value -> System.out.print(value + " "));
    System.out.println();

    for (int i = 0; i < arr.length-1; i++) {
        for (int j = 0; j < arr.length-i-1; j++) {
            count++;
            if (arr[j] > arr[j+1]) {
                swap(arr, j, j+1);
            }
        }
    }

    System.out.println("After BubbleSort Result");
    System.out.println("The number of count : " + count);
    Arrays.stream(arr).forEach(value -> System.out.print(value + " "));
    System.out.println();
}
public static void ImprovedBubbleSort(int[] arr){

    System.out.println("Before ImprovedBubbleSort");
    Arrays.stream(arr).forEach(value -> System.out.print(value + " "));
    System.out.println();

    int swapped = 1;
    int count = 0;
    for (int i = 0; i < arr.length-1; i++) {

        // 교환할 필요가 없다면 loop를 빠져나온다.
        // 회전 loop 단계에서 swap = 0이면 break
        if(swapped==0 ){
            break;
        }
        swapped = 0;
        for (int j = 0; j < arr.length-i-1; j++) {
            count++;
            if (arr[j] > arr[j+1]) {
                swap(arr, j, j+1);
                swapped = 1;
            }
        }
    }

    System.out.println("After ImprovedBubbleSort Result" );
    System.out.println("The number of count : " + count);
    Arrays.stream(arr).forEach(value -> System.out.print(value + " "));
    System.out.println();


}

public static void main(String[] args) {

    int[] arr1 = new int[]{10,9,8,7,6,5,4,3,2,1};
    int[] arr2 = new int[]{10,9,8,7,6,5,4,3,2,1};

    int[] arr3 = new int[]{1,2,3,4,5,6,7,8,9,10};
    int[] arr4 = new int[]{1,2,3,4,5,6,7,8,9,10};

    bubbleSort(arr1);
    System.out.println();
    ImprovedBubbleSort(arr2);
    System.out.println();
    bubbleSort(arr3);
    System.out.println();
    ImprovedBubbleSort(arr4);

}

}

```java
Before BubbleSort
10 9 8 7 6 5 4 3 2 1 
After BubbleSort Result
The number of count : 45
1 2 3 4 5 6 7 8 9 10 

Before ImprovedBubbleSort
10 9 8 7 6 5 4 3 2 1 
After ImprovedBubbleSort Result
The number of count : 45
1 2 3 4 5 6 7 8 9 10 

Before BubbleSort
1 2 3 4 5 6 7 8 9 10 
After BubbleSort Result
The number of count : 45
1 2 3 4 5 6 7 8 9 10 

Before ImprovedBubbleSort
1 2 3 4 5 6 7 8 9 10 
After ImprovedBubbleSort Result
The number of count : 9
1 2 3 4 5 6 7 8 9 10 

성능
최악의 경우 복잡도 :O(n2)
최선의 경우 복잡도: O(n)
평균 복잡도 : O(n2)
최악의 경우 공간 복잡도: O(1) 보조공간