Pattern double sided arrow

#1

i’m not able to built logic, please provide me help

#2

@aroshmishra2000_6c2ffe6238d74e2a
In Pattern Question, there is a common method which we teach in course viz, taking nsp, nst, csp, cst and row variables.

Pattern Hack: Always first Try to first print pattern by ignoring the value to be printed then accommodate your value in that pattern. For e.g.,

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

View it as:-

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

Short Info about the variables:-

  1. nsp (number of spaces)-> Number of spaces in very First Line of the pattern.
  2. nst (number of stars)-> Number of stars in very first line of the pattern.
  3. csp (counter of spaces)-> counter of spaces that will print the required number of spaces and will be initialized with 1 and incremented upto nsp.
  4. cst (counter of stars)-> counter of spaces that will print the required number of stars and will be initialized with 1 and incremented upto nst.
  5. rows -> It will be initialized with 1 and will go upto the total number of rows in the pattern.
    –Input N is the number of rows.Given pattern is seen as first spaces ,then numbers ,then spaces and then numbers again. Till middle row, number of numbers in one batch in a row is equal to row number. After middle row, number of numbers decreases each time by 1.The max value in the pattern is in the middle row which is (N/2 +1).

–So do the work of spaces first ,then that of numbers in decreasing order, then that of spaces and then that of numbers in increasing order.

Code:

import java.util.Scanner;
public class patternDSA {

public static void main(String[] args) {

    Scanner scn = new Scanner(System.in) ;
    int n = scn.nextInt() ;    // number of rows
    int nsp1 = n - 1;       // initializing number of spaces of 1st batch
    int nsp2 = -1;          // initializing number of spaces of 2nd batch
    int nst = 1;            // initializing number of numbers

    for (int row = 1; row <= n; row++) {

        int val;     // starting value of numbers

        if (row <= n / 2 + 1) {
            val = row;               // till mid value is equal to row number
        } else {
            val = n - row + 1;     // after mid values are total rows - current row +1
        }

          // work for spaces
        for (int csp = 1; csp <= nsp1; csp++) {
            System.out.print("  ");
        }

         // work for numbers
        for (int cst = 1; cst <= nst; cst++) {
            System.out.print(val + " ");
            val-- ;
        }

          // work for spaces
        for (int csp = 1; csp <= nsp2; csp++) {
            System.out.print("  ");
        }

        int cst = 1;
        val++ ;
        if (row == 1 || row == n) {
            cst = 2;

        }

        // work for numbers
        for (; cst <= nst; cst++) {
            System.out.print(val + " ");
            val++ ;
        }

        //preparation for next iteration
        if (row <= n / 2) {
            nsp1 -= 2;
            nst++;
            nsp2 += 2;
        } else {
            nsp1 += 2;
            nst--;
            nsp2 -= 2;
        }
        System.out.println();
    }
}

}

#3

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