CODEWITHSUNDEEP
java
rickygrimes
rickygrimes

Reputation: 2716

Print rows and columns alternately in a two-dimensional array

I have the below code for printing a two-dimensional array. I would like to print rows and columns in this array alternately. 

public class TwoDimensionalArrays {
public static void main(String[] args) {
    int marks[][]={{1,2,3},{4,5,6},{7,8,9}};

    for(int j=0;j<marks[0].length;j++) {
        for(int i=0;i<marks.length;i++) {

        }

    }
}

This is how I'd like my output to look. 

1 2 3
1 4 7
5 6
5 8
9

How can I tackle this?

Upvotes: 0

Views: 83

Answers (3)

McLovin
McLovin

Reputation: 1591

The key is setting i = j in the nested for loops

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

    if (j == marks.length - 1)
        break;
    for (int i = j; i < marks.length; i++) {
        System.out.print(marks[i][j] + " ");
    }
    System.out.println();
}

Upvotes: 1

Avantol13
Avantol13

Reputation: 1059

This works. Lots of confusing i's and j's, but it outputs what you want.

public static void main(String[] args) 
{
    int marks[][]={{1,2,3},{4,5,6},{7,8,9}};

    for(int j = 0; j < marks[0].length; j++) 
    {
        //Row across
        for(int i = j; i < marks.length; i++) 
        {
            System.out.print(marks[j][i] + " ");
        }
        System.out.println();

        //Column down
        if (j != marks[0].length - 1) //so we don't print 9 twice
        {
            for(int i = j; i < marks.length; i++) 
            {
                System.out.print(marks[i][j] + " ");
            }
            System.out.println();
        }
    }
}

Upvotes: 0

Tavo
Tavo

Reputation: 3151

This is a solution that will print what you need. Please be aware that you might need to do something with that ArrayIndexOutOfBoundsException

    for(int j=0;j<marks[0].length;j++) {
        System.out.println();
        for(int i=0;i<marks.length;i++) {
            try {
                System.out.print(marks[j][i+j]);
            } catch (ArrayIndexOutOfBoundsException e) {
                //do nothing
            }
        }
        System.out.println();
        for(int i=0;i<marks.length;i++) {
            try {
                if(j < marks.length-1) {
                    System.out.print(marks[i + j][j]);
                }
            } catch (ArrayIndexOutOfBoundsException e) {
                //do nothing
            }
        }
    }

Upvotes: 0

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