CODEWITHSUNDEEP
javafor-loop
Jay
Jay

Reputation: 245

need help on simple Java pattern coding

I am to make this following pattern on a for loop:

XXXXXXXXXX
XXXXXXXXXY
XXXXXXXXYY
XXXXXXXYYY
...

..and so on 

public class ex{
    public static void main(String[] args){
            for(int i=0;i<=10;i++){
                    System.out.println();
                    for(int j=0;j<=10;j++){
                            if(i==0){
                                    System.out.print("X");
                            }

                            if(i==1){
                                    System.out.print("X");
                                    if(j==9){
                                            System.out.print("Y");
                                    }
                            }
                    }
            }
    }

} ~

I am getting extra "X" at the end for my output that I don't want. I think there is a better way to do this but can't think of a way right now

Any help guys?

Upvotes: 2

Views: 406

Answers (6)

Paul
Paul

Reputation: 141829

Try nesting two loops inside one loop. Count up to i and then continue counting up to 10 on each iteration of the outer loop:

// 10 lines
for(int i = 10; i >= 0; i--){

    int j = 0; 

    // Print 'X's (10 - i of them)
    for(; j < i; j++)
        System.out.print("X");

    // Print 'Y's (i of them)
    for(; j < 10; j++)
        System.out.print("Y");

    System.out.println();
}

Upvotes: 3

tibtof
tibtof

Reputation: 7957

The condition for the / diagonal of a matrix is i + j = n, so the left-upper part is i + j < n and i + j > n for the right-lower part.

public static void main(String... arg) {
    int n = 10;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if ( i + j < n) {
                System.out.print("X");
            } else {
                System.out.print("Y");
            }
        }
        System.out.println();
    }
}

If you want to separate on \ diagonal, the condition for the diagonal is i = j, for the upper part i > j and for the lower part i < j.

Upvotes: 0

Markus Mikkolainen
Markus Mikkolainen

Reputation: 3497

hint: each row is of the same length, there is just one less X and one more Y on each row down. 

public class XY
{
        public static void main(String[] args)
        {
                System.out.print(xy(10,10));
        }
        public static String xy(int rows,int origRows)
        {
                return X(rows,origRows-rows)+"\n"+((rows>0)?xy(rows-1,origRows):"");
        }
        public static String X(int x,int y)
        {
                return (x>0?"X":"")+((x>0||y>0)?X(x-1,y-1):"")+(y>0?"Y":"");
        }
}

teehee.

Upvotes: 0

Nathaniel Ford
Nathaniel Ford

Reputation: 21220

Here is a recursive solution:

 public class ex {
    public static final String X = "X";
    public static final String Y = "Y";

    public static void main(String[] args){
      printall(10, 0);
    }

    private static void printall(int length, int saturation){
      if (saturation > length) {
        return;
      } else {
        System.out.print(printRow(length, saturation, 0);
        printall(length, saturation + 1);
      }
    }

    private static String printrow(int length, int saturation, int position) {
      if (position > length) {
        return "";
      } else {
        return getChar(length, saturation, position) + printrow(length, saturation, position + 1);
      }
    }

    private static String getChar(int length, int saturation, int position) {
      if (length-saturation < position) {
        return Y;
      } else {
        return X;
      }
    }
  }

Upvotes: 0

Matt
Matt

Reputation: 17629

Probably not the most efficient version, but here it goes:

public static void main(String[] args) {
    for (int i = 0; i <= 10; i++) {
        System.out.println(repeat("X", 10 - i) + repeat("Y", i));
    }
}

private static String repeat(String string, int times) {
    return new String(new char[times]).replaceAll("\0", string);
}

Upvotes: 0

Baltasarq
Baltasarq

Reputation: 12202

The answer to your specific question is:

for(int i=0;i<=10;i++)

i<=10 should be i<10, since from 0 to 10 (inclusive) there are eleven loops.

Upvotes: 0

Related Questions