loop problem

[kabi Rabbi]

Problem: Observe that its base and height are both equal to, and the image is drawn using # symbols and spaces. The last line is not preceded by any spaces.

Write a program that prints a staircase of size.

The output of the program should be like this for n=4.
          #
       ##
   ###
####

My issue in this problem:  The output(for n=4) is
#
##
###
####

can you please help me out? what I'm doing wrong in my code. Thanks. The code is given below.

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    // Complete the staircase function below.
    static void staircase(int n) {
               int k;
               for(int i=0;i<n;i++){
                   for( k=n;k<i;k--){
                       System.out.print(" ");   
                   }  
                      for(int j=0;j<i;j++){
                       
                          System.out.print("#");
                          
                      }
                         System.out.println();
                
               }

    }

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        int n = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        staircase(n);

        scanner.close();
    }
}

[Campbell Ritchie]

How did you design that program? What pseudo‑code did you use? Those staircase programs can be annoying, but proper design in advance will beat them into submission.

[Eric Arnold]

Is uh, this what you're hoping to achieve?

    static void staircase(int n) {
        StringBuilder sb = new StringBuilder("#");
        for(int i = 0 ; i < n; i++)
            sb.insert(0, " ");
        for(int j = 0; j < n; j++) {
            System.out.println(sb.toString());
            sb.deleteCharAt(0);
            sb.append("#");
        }
        System.out.println();
    }

[Campbell Ritchie]

I would use a StringBulder myself, to improve performance over multiple System.out.println calls. I wouldn't call toString() on it, nor would I do any removal. Nor would I use the insert() method. I would add all the lines to my StringBuilder, so only one println call would be necessary. I personally would use a separate method to create the lines.
But the real problem OP is facing is working out the loops. I would like to know how he calculated the number of spaces and of hash signs, since that is not clear from the code. The code looks like what happens when you simply shove bits of code together without planning, though I do find that sort of staircase program awkward to write myself. That is why it is a worthwhile exercise: it makes people think about how many times each loop will run.
The worst error is in line 37.

OP: Please tell the full details. You described an output, but I got a different output from that.

[salvin francis]

@Campbell, How about using characters instead of Strings ? That would probably boost the program even more. I see that just 3 characters: ' ','#', and '\n' are needed.
@OP, the only import you need is

import java.util.Scanner;

I am not sure why you are using scanner.skip, maybe you can elaborate more on that ?

[Juan Pablo Barale]

Hi @Kabi, you can do something like this:

// Complete the staircase function below.
    static void staircase(int n) {
      StringBuilder sb = new StringBuilder();
      for(int i = 0; i < n; i++){
        int k = 0;
        // adds blank prefixes
        for(; k < n - i; k++) {
          sb.append(" ");   
        }  
        // adds # symbols
        for(int j = k; j <= n; j++){                        
          sb.append("#");         
        }
        sb.append("\n");
      }
      System.out.println(sb.toString());
    }
 
    public static void main(String[] args) {   
        staircase(14);
    }

You need to print n lines, all with the same length:
n-1 blanks + 1 #
n-2 blanks + 2 #
.
.
.
n-(n-1) blanks + n-1 #
0 blanks + n #

hope this helps

[Liutauras Vilda]

Guys, two of you already started providing complete solutions, that is of no good for OP.
That way we are simply robbing from OP an ability to come up with his/her own piece of solution he/she could proud of.

We're all here to learn, so when responding to others, please focus on helping them discover their own solutions, instead of simply providing answers.

[Eric Arnold]

Aye, I apologize.

[Campbell Ritchie]

Apologies accepted