﻿ Java - Make a staircase of n coins with k coins in every row

# Java: Form a staircase shape of n coins where every k-th row must have exactly k coins

## Java Basic: Exercise-109 with Solution

Write a Java program to form a staircase shape of n coins where every k-th row must have exactly k coins.

Example 1:
n = 3
The coins can form the following rows:
\$
\$ \$
We will return 2 rows.
Example 2:
n = 4
The coins can form the following rows:
\$
\$ \$
\$
We will return 2 rows as the 3rd row is incomplete.
Example 3:
n = 5
The coins can form the following rows:
\$
\$ \$
\$ \$
We will return 2 rows as the 3rd row is incomplete.

Sample Solution:

Java Code:

``````import java.util.Scanner;

public class Example109 {
public static void main(String[] arg) {
// Create a Scanner object for user input
Scanner in = new Scanner(System.in);

// Prompt the user to input a positive integer
System.out.print("Input a positive integer: ");

// Read the user's input as an integer
int n = in.nextInt();

if (n > 0) {
// Check if n is a positive integer
double sqrtResult = Math.sqrt(8 * (long) n + 1);  // Calculate the square root
int numRows = (int) ((sqrtResult - 1) / 2);      // Calculate the number of rows
System.out.println("Number of rows: " + numRows);
}

// Close the input scanner
in.close();
}
}
```
```

Sample Output:

```Input a positive integer: 5
Number of rows: 2
```

Flowchart: Java Code Editor:

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