Java Pattern Problem

Readul Islam Niyon — Tue, 11 Oct 2022 14:45:31 +0000

Java solution to 24 pattern problems

simple logic behind pattern problems

The number of rows in the pattern are executed by the outer loop.
Inner loop executes over number of columns (calculate column number)
The elements need to print in each column
Careful about new lines and spaces

Pattern 1


     *
     * *
     * * *
     * * * *
     * * * * *



   public static void main(String[] args) {

        // number of lines in the pattern
        int n = 5;
        //outer loop iterates over n;
        for(int row = 1; row <=n; row++){
            //inner loop iterates over row;
            for(int col = 1; col <=row; col++){
                //print *;
                System.out.print("* ");
            }
            //print new line;
            System.out.println();
        }
    }

Pattern 2


     * * * * *
     * * * *
     * * *
     * *
     *



 public static void main(String[] args) {
        // number of lines in the pattern;
        int n = 5;
        // outer loop iterates over number of lines;
        for(int row = 1; row <= n; row++) {
            // inner loop iterates over the formula (n + 1)-row ;
            for(int col = 1; col <= n+1-row; col++) {
                //print *
                System.out.print("* ");
            }
            // add new line
            System.out.println();
        }
    }

Pattern 3



1
1 2
1 2 3
1 2 3 4
1 2 3 4 5


 public static void main(String[] args) {
        // number of lines in the pattern
        int n = 5;
        //outer loop iterates over n;
        for(int row = 1; row <=n; row++){
            //inner loop iterates over row;
            for(int col = 1; col <=row; col++){
                //print *;
                System.out.print(col + " ");
            }
            //print new line;
            System.out.println();
        }
    }

Pattern 4



     *
     * *
     * * *
     * * * *
     * * * * *
     * * * *
     * * *
     * *
     *


public static void main(String[] args) {
        // number of lines look similar
        int n = 5;
        // outer loop iterates over number of lines in the pattern
        for(int row = 1; row < 2*n; row++) {
            // calculate number of columns in a row
            int noOfCol = row > n ? 2*n - row : row;
            // inner loop iterates over number of columns
            for(int col = 1; col <= noOfCol; col++) {
                // print *
                System.out.print("* ");
            }
            // add new line after every row
            System.out.println();
        }

    }

Pattern 5



     * * * * *
     * * * *
     * * *
     * *
     *
     * *
     * * *
     * * * *
     * * * * *


  public static void main(String[] args) {
        // number of lines look similar
        int n = 5;
        // outer loop iterates over number of lines in the pattern
        for(int row = 1; row < 2*n; row++){
            // calculate number of columns in a row
            int noOfCols = row > n ? row+1-n : n+1-row;
            // inner loop iterates over number of columns
            for(int col = 1; col <= noOfCols; col++) {
                // print *
                System.out.print("* ");
            }
            // After printing each row, add a new line
            System.out.println();
        }

    }

Pattern 6



     *
     * *
     * * *
     * * * *
     * * * * *
     * * * * *
     * * * *
     * * *
     * *
     *


  public static void main(String[] args) {
        // number of lines look similar
        int n = 5;
        // outer loop iterates over number of lines in the pattern
        for(int row = 1; row <= 2*n; row++) {
            // calculate number of columns in a row
            int noOfCol = row > n ? 2*n - row+1 : row;
            // inner loop iterates over number of columns
            for(int col = 1; col <= noOfCol; col++) {
                // print *
                System.out.print("* ");
            }
            // add new line after every row
            System.out.println();
        }
    }

Pattern 7



     * * * * *
     * * * *
     * * *
     * *
     *
     *
     * *
     * * *
     * * * *
     * * * * *


    public static void main(String[] args) {
        // number of similar lines that don't repeated
        int n = 5;
        // outer loop iterates over number of lines
        for(int row = 1; row <=2*n; row++) {
            // calculate the number of columns in each row
            int noOfCols = row > n? row - n : (n+1)-row ;
            // inner loop iterates over number of columns
            for(int col = 1; col <= noOfCols; col++) {
                // print *
                System.out.print("* ");
            }
            // after printing each row, add a new line
            System.out.println();
        }
    }

Pattern 8



             *
           * *
         * * *
       * * * *
     * * * * *


    public static void main(String[] args) {
        // number of lines in the pattern
        int n = 5;
        // outer loop iterates over Number of lines which is rows
        for(int row = 1; row <= n; row ++) {
            // number of columns for printing space
            int noOfSpaces = n-row;
            // inner loop iterates over Number of spaces
            for(int space = 1; space <= noOfSpaces; space ++) {
                System.out.print("  ");
            }
            // number of columns for printing star
            int noOfStars = row;
            // inner loop iterates over Number of stars
            for(int star = 1; star <= noOfStars; star ++) {
                System.out.print("* ");
            }
            // after printing each row, add a new line
            System.out.println();
        }
    }

Pattern 9



     * * * * *
       * * * *
         * * *
           * *
             *



   public static void main(String[] args) {


        // number of lines in the pattern
        int n = 5;

        // outer loop iterates over Number of lines which is rows
        for(int row = 1; row <= n; row ++) {
            // number of columns for printing space
            int noOfSpaces = row-1;

            // inner loop iterates over Number of spaces
            for(int space = 1; space <= noOfSpaces; space ++) {
                System.out.print("  ");
            }

            // number of columns for printing star
            int noOfStars = n+1-row;

            // inner loop iterates over Number of stars
            for(int star = 1; star <= noOfStars; star ++) {
                System.out.print("* ");
            }
            // after printing each row, add a new line
            System.out.println();
        }
    }

Pattern 10



           *
         * * *
       * * * * *
     * * * * * * *
   * * * * * * * * *



    public static void main(String[] args) {

        // number of lines in the pattern
        int n = 5;
        // outer loop executes until the number of lines is reached
        for(int row = 1; row <=n; row++) {
            // number of spaces in the columns
            int noOfSpaces = n - row;
            // inner loop executes until the number of spaces  is reached
            for(int space = 1; space <=noOfSpaces; space++) {
                System.out.print("  ");
            }
            // number of stars in the columns
            int noOfStars = row + row-1;
            // inner loop executes until the number of stars is reached
            for(int star = 1; star <= noOfStars; star++) {
                System.out.print("* ");
            }
            // after printing each row,add a new line
            System.out.println();
        }

    }

Pattern 11



     * * * * * * * * *
       * * * * * * *
         * * * * *
           * * *
             *


    public static void main(String[] args) {

        // number of lines in the pattern
        int n = 5;
        // outer loop executes until the number of lines is reached
        for(int row = 1; row <=n; row++) {
            // number of spaces in the columns
            int noOfSpaces = row-1;
            // inner loop executes until the number of spaces  is reached
            for(int space = 1; space <=noOfSpaces; space++) {
                System.out.print("  ");
            }
            // number of stars in the columns
            int noOfStars = 2* (n-row)+1;
            // inner loop executes until the number of stars is reached
            for(int star = 1; star <= noOfStars; star++) {
                System.out.print("* ");
            }
            // after printing each row,add a new line
            System.out.println();
        }

    }

Pattern 12



         *
        * *
       * * *
      * * * *
     * * * * *


    public static void main(String[] args) {

        // number of lines in the pattern
        int n = 5;
        // outer loop iterates over Number of lines which is rows
        for(int row = 1; row <= n; row ++) {
            // number of columns for printing space
            int noOfSpaces = n-row;
            // inner loop iterates over Number of spaces
            for(int space = 1; space <= noOfSpaces; space ++) {
                System.out.print(" ");
            }
            // number of columns for printing star
            int noOfStars = row;
            // inner loop iterates over Number of stars
            for(int star = 1; star <= noOfStars; star ++) {
                System.out.print("* ");
            }
            // after printing each row, add a new line
            System.out.println();
        }
    }

Pattern 13



     * * * * *
      * * * *
       * * *
        * *
         *


   public static void main(String[] args) {

        // number of lines in the pattern
        int n = 5;
        // outer loop iterates over Number of lines which is rows
        for(int row = 1; row <= n; row ++) {
            // number of columns for printing space
            int noOfSpaces = row-1;
            // inner loop iterates over Number of spaces
            for(int space = 1; space <= noOfSpaces; space ++) {
                System.out.print(" ");
            }
            // number of columns for printing star
            int noOfStars = n-row+1;
            // inner loop iterates over Number of stars
            for(int star = 1; star <= noOfStars; star ++) {
                System.out.print("* ");
            }
            // after printing each row, add a new line
            System.out.println();
        }
    }

Pattern 14



     * * * * *
      * * * *
       * * *
        * *
         *
         *
        * *
       * * *
      * * * *
     * * * * *


    public static void main(String[] args) {
        // number of lines in the pattern which is rows
        int N = 10;
        // number of similar lines in the pattern
        int n = 5;
        // outer loop iterates over the number of lines N
        for (int row = 1; row <= N; row++) {
            // number of spaces in the column
            int noOfSpaces = row > n ? N - row : row - 1;
            // inner loop iterates over the number of spaces
            for(int space = 1; space <= noOfSpaces; space++) {
                System.out.print(" ");
            }
            // number of stars in the column
            int noOfStars = row > n ? row-n : n-row+1;
            // inner loop iterates over the number of stars
            for(int stars = 1; stars <= noOfStars; stars++) {
                System.out.print("* ");
            }
            // add a new line after printing rows
            System.out.println();
        }
    }

Pattern 15




    *
   * *
  *   *
 *     *
*********


   public static void main(String[] args) {

        // number of lines in the pattern
        int n = 5;
        // outer loop will be executed till the number of lines
        for(int row = 1; row <=n; row++) {
            // number of spaces in the column before printing star
            int noOfSpaces = n -row;
            //inner loop executes until the noOfSpaces is reached
            for(int space = 1; space <=noOfSpaces; space++) {
                // print spaces
                System.out.print(" ");
            }
            // number of stars and spaces in the pattern
            int noOfStars = row + row -1;
            // inner loop executes until the noOfStars is reached
            for(int star = 1; star <= noOfStars; star++){
                // print stars in first, last in the column and last row
                if(star ==1 || star == noOfStars || row == n){
                    System.out.print("*");
                }
                // otherwise print spaces
                else System.out.print(" ");

            }
            // adding a new line after printing each row
            System.out.println();
        }

    }

Pattern 16



     *********
      *     *
       *   *
        * *
         *


    public static void main(String[] args) {

        // number of lines in the pattern
        int n = 5;
        // outer loop will be executed till the number of lines
        for(int row = 1; row <=n; row++) {
            // number of spaces in the column before printing star
            int noOfSpaces = row-1;
            //inner loop executes until the noOfSpaces is reached
            for (int space = 1; space <= noOfSpaces; space++) {
                // print spaces
                System.out.print(" ");
            }
            // number of stars and spaces in the pattern
            int noOfStars = 2*n-row- noOfSpaces;
            // inner loop executes until the noOfStars is reached
            for (int star = 1; star <= noOfStars; star++) {
                // print stars in first, last in the column and last row
                if (star == 1 || star == noOfStars || row == 1) {
                    System.out.print("*");
                }
                // otherwise print spaces
                else System.out.print(" ");

            }
            // adding a new line after printing each row
            System.out.println();
        }
    }

Pattern 17



     *****
     *   *
     *   *
     *   *
     *****


   public static void main(String[] args) {

        // number of lines in the pattern
        int l = 5;
        // outer loop executes over l
        for(int row = 1; row <=l; row ++) {
            // number of stars and spaces in a row;
            int noOfStars = l ;
            // inner loop executes over noOfStars;
            for(int star = 1; star <=noOfStars; star ++) {
                // print star in column first,column last, row first and row last positions
                if(star == 1 || star == noOfStars || row == l || row == 1){
                    System.out.print("*");
                }
                // print spaces
                else System.out.print(" ");
            }
            // add a new line after each row
            System.out.println();
        }

    }

Pattern 18



     * * * * *
      * * * * *
       * * * * *
        * * * * *
         * * * * *


    public static void main(String[] args) {

        // total lines in the pattern
        int l = 5;

        // outer loop executes over the l
        for(int row = 1; row <= l; row++) {

            // number of Spaces before printing stars
            int noOfSpaces = row - 1;
            // inner loop executes over noOFSpaces;
            for(int space = 1; space <= noOfSpaces; space++) {
                // print space
                System.out.print(" ");
            }
            // number of stars;
            int noOfStars = l;
            // inner loop executes over noOfStars;
            for(int star = 1; star <= noOfStars; star++) {
                // print star
                System.out.print("* ");
            }
            // add a new line before executes next row
            System.out.println();
        }
    }

Pattern 19



         *****
        *   *
       *   *
      *   *
     *****


    public static void main(String[] args) {

        // number of lines in the pattern
        int l = 5;
        // outer loop for executing the number of rows which is equal to number of lines l
        for(int row = 1; row <=l; row ++) {

            // number of spaces in the column before printing stars
            int noOfSpaces = l - row;
            // inner loop executes over noOfSpaces
            for(int spaces = 1; spaces <= noOfSpaces; spaces++) {
                // print stars before printing stars
                System.out.print(" ");
            }
            // number of stars and middle spaces
            int noOfStars = l;
            // inner loop executes over noOfStars
            for(int stars = 1; stars <=noOfStars; stars++) {
                // print stars in  first and last position of column and row
                if(stars == 1 || stars == noOfStars || row == 1 || row == l){
                    System.out.print("*");
                }
                // otherwise print middle spaces
                else System.out.print(" ");
            }
            // add a new line after each row
            System.out.println();
        }
    }

Pattern 20



     *****
      *   *
       *   *
        *   *
         *****



   public static void main(String[] args) {

        // number of lines in the pattern
        int l = 5;
        // outer loop for executing the number of rows which is equal to number of lines l
        for(int row = 1; row <=l; row ++) {

            // number of spaces in the column before printing stars
            int noOfSpaces = row -1;
            // inner loop executes over noOfSpaces
            for(int spaces = 1; spaces <= noOfSpaces; spaces++) {
                // print stars before printing stars
                System.out.print(" ");
            }
            // number of stars and middle spaces
            int noOfStars = l;
            // inner loop executes over noOfStars
            for(int stars = 1; stars <=noOfStars; stars++) {
                // print stars in  first and last position of column and row
                if(stars == 1 || stars == noOfStars || row == 1 || row == l){
                    System.out.print("*");
                }
                // otherwise print middle spaces
                else System.out.print(" ");
            }
            // add a new line after each row
            System.out.println();
        }
    }

Pattern 21




     *
    * *
   *   *
  *     *
 *       *
  *     *
   *   *
    * *
     *



    public static void main(String[] args) {
        // number of lines
        int l = 9;
        // number of similar lines
        int n = l/2+1;
        // outer loop iterates over l;
        for(int row = 1; row <= l; row++) {
            // number of spaces before printing each column
            int noOfSpaces = row > n ? row - n : n - row ;
            // inner loop iterates over noOfSpaces;
            for(int space = 1; space <= noOfSpaces; space++) {
                // print spaces
                System.out.print(" ");
            }
            // number of stars in a column
            int noOfStars = row > n ?  2*n - row : row ;
            // inner loop iterates over noOfStars;
            for(int star = 1; star <= noOfStars; star++) {
                // star print in first and last column in a row
                if(star == 1 || star == noOfStars) {
                    System.out.print("* ");
                }
                // otherwise print spaces
                else System.out.print("  ");
            }
            // add a new line after each row
            System.out.println();
        }
    }

Pattern 22



        1
       1 1
      1 2 1
     1 3 3 1
    1 4 6 4 1



    public static void main(String[] args) {

        // number of lines
        int n = 5;
        // outer loop iterates over n;
        for(int row = 1; row <= n; row++) {
            // set num = 1;
            int num = 1;
            // number of spaces before printing elements
            int noOfSpaces = n - row ;
            // outer loop iterates over noOfSpaces;
            for(int space = 1; space <= noOfSpaces; space++) {
                // print spaces
                System.out.print(" ");
            }
            // inner loop iterates over row;
            for(int col = 1 ; col <= row; col++) {
                // print num;
                System.out.print(num + " ");
                // update num value for next number
                num = num * (row - col)/ (col);
            }
            // add a new line
            System.out.println();
        }
    }

Pattern 23




   1
  212
 32123
4321234
 32123
  212
   1



    public static void main(String[] args) {

        // number of input
        int n = 4;
        // number of lines
        int N = 2*n-1;
        // outer loop iterates over N;
        for(int row = 1; row <= N; row++) {
            // number of spaces in a row
            int noOfSpaces = row > n ? row - n : n - row ;
            // inner loop iterates over noOfSpaces;
            for(int space = 1; space <= noOfSpaces; space++) {
                // print space
                System.out.print(" ");
            }
            // number of cols c;
            int c = row > n ? 2*n-row : row ;
            // from c to 1
            for(int col = c; col >= 1 ; col--) {
                System.out.print(col);
            }
            // from 2 to c;
            for(int col = 2; col <=c ; col++) {
                System.out.print(col);
            }
            System.out.println();
        }
    }

Pattern 24




1
0 1
1 0 1
0 1 0 1
1 0 1 0 1



    public static void main(String[] args) {
        // number of lines
        int n = 5;
        // outer loop iterates over n;
        for (int row = 1; row <= n; row++) {

            // inner loop executes each col till number of rows;
            for (int col = 1; col <= row; col++) {
                // print 1 for even
                if ((row + col) % 2 == 0) {
                    System.out.print(1+ " ");
                }
                // print 0 for odd
                else {
                    System.out.print(0+ " ");
                }
            }
            // add a new line
            System.out.println();
        }
    }

DEV Community: Readul Islam Niyon

Java Pattern Problem

Java solution to 24 pattern problems

Pattern 1

Pattern 2

Pattern 3

Pattern 4

Pattern 5

Pattern 6

Pattern 7

Pattern 8

Pattern 9

Pattern 10

Pattern 11

Pattern 12

Pattern 13

Pattern 14

Pattern 15

Pattern 16

Pattern 17

Pattern 18

Pattern 19

Pattern 20

Pattern 21

Pattern 22

Pattern 23

Pattern 24