PattenOne

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
class PatternOne{
    static int getInput(String prompt){
        System.out.print(prompt);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        while(true){
            try{
                return Integer.parseInt(br.readLine());
            } catch(IOException | NumberFormatException nfe){
                System.out.print("Exception in input! Try again: ");
            }
        }
    }
    public static void main(String args[]){
        int i, j, n = getInput("Enter the number of rows:  ");
        for(i = 1; i <= n; i++){
                for(j = 1; j <= i; j++) System.out.print(j);
                for(j = 0; j < (n*2-i*2); j++) System.out.print(" ");
                for(j = i; j > 0; j--) System.out.print(j);
                System.out.println();
        }
    }
}
//Output:-
// Enter the number of rows:  6
// 1          1
// 12        21
// 123      321
// 1234    4321
// 12345  54321
// 123456654321