Question

/**
 * This program will sort an n by n array by the first value in each row.
 * Selection sort algorithm is modified to do the sorting.
 * For example:
 * <p/>
 * If the original array is:
 * 1  2  3  4  5
 * 3  4  5  1  2
 * 5  2  3  4  1
 * 2  3  1  4  5
 * 4  2  3  1  5
 * <p/>
 * The array after sorting is:
 * 1  2  3  4  5
 * 2  3  1  4  5
 * 3  4  5  1  2
 * 4  2  3  1  5
 * 5  2  3  4  1
 *
 * @author YOUR NAME
 * @version 09/29/2020
 */
public class ArraySortByFirst
{
    private int[][] dataToSort;

    public ArraySortByFirst(int[]... data)
    {
        this.dataToSort = data;
    }

    /**
     * Task: Sorts an array of integers by the first value of each row. After
     * sorting, the first column of the array is in ascending order.
     */
    public void sortByFirstColumn()
    {
        //TODO Project2
        // I am similar to selection sort");

    }

    /**
     * Task: Finds the row of the smallest value in the first column of this.dataToSort array.
     *
     * @param first the index of the first array row to consider
     * @param last  the index of the last array row to consider
     * @return the index of the row with the smallest element in the first column among
     * this.dataToSort[first], this.dataToSort[first + 1], . . . , this.dataToSort[last]
     */
    private int getIndexOfSmallest(int first, int last)
    {
        int min = this.dataToSort[first][0];
        int indexOfMin = first;

        //TODO Project2

        return indexOfMin;
    }

    /**
     * Task: Swaps the rows  this.dataToSort[i] and this.dataToSort[j].
     *
     * @param i row to swap
     * @param j row to swap
     */
    private void swap(int i, int j)
    {

        //TODO Project2

    }

    /**
     * Task: displays the content of this.dataToSort row by row
     */
    public void display()
    {

        //TODO Project2 - implement first;


    }

    public static void main(String args[])
    {
        int array[][] = {{1, 2, 3, 4, 5}, {3, 4, 5, 1, 2}, {5, 2, 3, 4, 1}, {2, 3, 1, 4, 5}, {4, 2, 3, 1, 5}};

        ArraySortByFirst sortArray = new ArraySortByFirst(array);
        System.out.println("The original array is ");
        sortArray.display();
        System.out.println();

        sortArray.sortByFirstColumn();
        System.out.println("The array after sorting is ");
        sortArray.display();
        System.out.println();
    } // end main
} // end ArraySortByFirst

Answer 1

code:

public class ArraySortByFirst {

private int[ ] [ ] dataToSort;

public ArraySortByFirst(int[]....data)

{

this.dataToSort = data;

}

public void sortByFirstColumn()

{

for(int i=0;; i<dataToSort.length; i++)

{

int leastElementRow=getIndexOfSmallest(i,dataToSort.length);

swap(i,leastElementRow);

}

}

private int getIndexOfSmallest(int first,int last)

{

int min=this.dataToSort[first][0];

int indexOfMin= first;

for(int i=first;i<last;i++){

if(dataToSort[i][0]<min){

min=dataToSort[i][0];

indexOfMin=i;

}

return indexOfMin;

}

private void swap(int i,int j)

{

int tempRow[]=dataToSort[i];

dataToSort[i]=dataToSort[j];

dataToSort[j]=tempRow;

}

public void display()

{

for(int i=0;i<dataToSort.length;i++){

for(int j=0;j<dataToSort.length;j++){

System.out.print(dataToSort[i][j]+" ");

}

System.out.println();

}

}

public static void main(String[] args){

int array[ ] [ ] ={ {1,2,3,4,5} , {3,4,5,1,2},{5,2,3,4,1} , {2,3,1,4,5},{4,2,3,1,5}};

ArraySortByFirst sortArray= new ArraySortByFirst(array);

System.out.println("The original array is ") ;

sortArray.display();

System.out.println();

sortArray.sortByFirstColumn();

System.out.println("The array after Sorting is ");

sortArray.display();

System.out.println();

}

}

}

screenshot of code :

screenshot of output: