program

Changing order of number

package pratice;

public class arr192837 {
    public static void main(String[] args) {
        int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
        int[] result = new int[arr.length];
        int left = 0;
        int rigth = arr.length - 1;
        for (int i = 0; i < arr.length; i++) {

            if (i % 2 == 0)
                result[i] = arr[left++];
            else
                result[i] = arr[rigth--];
        }
        for (int i = 0; i < arr.length; i++) {
            System.out.print(result[i] + " ");
        }
    }

}

Output:
1 9 2 8 3 7 4 6 5

Combine two array and duplicate element:

package pratice;

public class combine_2arr {
    public static void main(String[] args) {
        int[] arr1 = { 1, 2, 3, 4, 5, 6 };
        int[] arr2 = { 6, 7, 4, 9, 10 };
        for (int j = 0; j < arr1.length; j++) {
            int key = arr1[j];
            for (int i = 0 ; i < arr2.length ; i++) {
                if (key == arr2[i]) {
                    System.out.println("duplicate element in arr1 and arr2 = "+arr2[i]+" ");
                }
            }
        }
    }
}

Output:
duplicate element in arr1 and arr2 = 4
duplicate element in arr1 and arr2 = 6

bubblesort

package afterfeb13;

public class bubblesort {
    public static void main(String[] args) {
        int[] score = { 1,-1,1,-1,1,-1,1,-1 };

        for (int j = 1; j < score.length; j++)// running 7 time

        {
            for (int i = 0; i < score.length - j; i++) // j or 1 score.length-j change to index because index star from
                                                        // [0]
            // why j order index--decrese when number order ex{80,70,60,50,80,90,90} then
            // index decreaseex{80,70,60,50,80},
            {
                if (score[i] > score[i + 1])// 0>1,1>2,2>3,3>4
                {
                    int temp = score[i];
                    score[i] = score[i + 1];
                    score[i + 1] = temp;
                }

            }

        }
        for (int i = 0; i < score.length; i++) {
            System.out.print(score[i] + " ");
        }
    }

}

Output:
-1 -1 -1 -1 1 1 1 1