Expalin the answer -- Arrays

[Roopa Bagur]

19. If size = 4, triArray looks like:

int[][] makeArray( int size)
{ int[][] triArray = new int[size] [];
int val=1;
for( int i = 0; i < triArray.length; i++ )
{ triArray[i] = new int[i+1];
for( int j=0; j < triArray[i].length; j++ )
{ triArray[i][j] = val++;
}
}
return triArray;
}

a)
1 2 3 4
5 6 7
8 9
10
b)
1 4 9 16
c)
1 2 3 4
d)
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
e)
1
2 3
4 5 6
7 8 9 10

[Valentin Crettaz]

I think the right answer is e...
Try and run it but at a first sight e seems to be the right answer...
Val

[Ragu Sivaraman]

When you run it
it prints
1
2
3
4
5
6
7
8
9
10
So is both a and e correct?
I am confused
Can someone explain how the code is working?
Thankx

[Valentin Crettaz]

it's not a matter of printing it is a matter of HOW the arrays look like...
the first array has one element: 1
the second array has two elements: 2 3
the third array has three elements: 4 5 6
the fourth array has four elements: 7 8 9 10
so answer e is correct !!
Val

[Amit Agrawal]

public class tryOutPut {
// method to make 2D array.
int[][] makeArray( int size){
//  creating 2D array i.e., Array of Arrays.
int[][] triArray = new int[size] [];
// as you passed 4, it created an array of size 4, each element will hold
// one array (n their size will be determined at Run Time).

int val=1;
// a variable, which will be just incremented by one and would be assigned to elements of these arrays.
System.out.println("triArray.length of this 2 d Array " + triArray.length + " has to be same as size passed to it i.e. " + size);
for(int i = 0; i < triArray.length; i++ ) {
// loop to create those 4 arrays.

triArray[i] = new int[i+1];
// just creating arrays with size of plus one than its position.
// i.e array at zeroth position will have size 1, array at 2nd position
// will have size 3 ...
for( int j=0; j < triArray[i].length; j++ ){
// loop (for size of individual sub-arrays)
// to assign values to respective elements.

triArray[i][j] = val++;
// just assigning values in ascending order.
}
}
return triArray;
}
// trial code to run it.
public static void main(String args[]){
tryOutPut top = new tryOutPut();
int [][]a = top.makeArray(4);
for(int i = 0; i < a.length; i++ ) {
for( int j=0; j < a[i].length; j++ ){
System.out.print(a[i][j]);
}
System.out.println();
}
}
// ends here.

}
So The Answer is e.
1
23
456
78910

Originally posted by Roopa Bagur:
19. If size = 4, triArray looks like:

int[][] makeArray( int size)
{ int[][] triArray = new int[size] [];
int val=1;
for( int i = 0; i < triArray.length; i++ )
{ triArray[i] = new int[i+1];
for( int j=0; j < triArray[i].length; j++ )
{ triArray[i][j] = val++;
}
}
return triArray;
}

a)
1 2 3 4
5 6 7
8 9
10
b)
1 4 9 16
c)
1 2 3 4
d)
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
e)
1
2 3
4 5 6
7 8 9 10

[Valentin Crettaz]

Good job Amit !!
Val

[Roopa Bagur]

Excellent everybody thankyou

Originally posted by Roopa Bagur:
19. If size = 4, triArray looks like:

int[][] makeArray( int size)
{ int[][] triArray = new int[size] [];
int val=1;
for( int i = 0; i < triArray.length; i++ )
{ triArray[i] = new int[i+1];
for( int j=0; j < triArray[i].length; j++ )
{ triArray[i][j] = val++;
}
}
return triArray;
}

a)
1 2 3 4
5 6 7
8 9
10
b)
1 4 9 16
c)
1 2 3 4
d)
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
e)
1
2 3
4 5 6
7 8 9 10