Program to print hollow pyramid, diamond pattern and their modifications

For Prerequisite : Loops, If Else Statement
1. Hollow pyramid/triangle pattern
The pattern is similar to pyramid pattern. The only difference is, we will replace all internal ‘#’ or ‘*’ characters by space character and we will print 2*N-1 (N = number of rows in pattern) ‘#’ or ‘*’ characters in last row. 
Examples:

Input: n=6
Output:
     #
    # #
   #   #
  #     #
 #       #
#         #
###########    

C++14

// CPP program to print a hollow pyramid pattern
#include <iostream>
using namespace std;
void printPattern(int);
int main()
{
    int n = 6;

    printPattern(n);
}
void printPattern(int n)
{
    int i, j, k = 0;
    for (i = 1; i <= n; i++) // row=6
    {
        // Print spaces
        for (j = i; j < n; j++) {
            cout << " ";
        }
        // Print #
        while (k != (2 * i - 1)) {
            if (k == 0 || k == 2 * i - 2)
                cout << "#";
            else
                cout << " ";
            k++;
        }
        k = 0;
        cout << endl; // print next row
    }
    // print last row
    for (i = 0; i < 2 * n - 1; i++) {
        cout << "#";
    }
}
// this article is contributed by Shivani Ghughtyal

Java

// JAVA program to print a hollow
// pyramid pattern
class GFG{

    public static void main(String args[])
    {
        int n = 6;

        printPattern(n);
    }

    static void printPattern(int n)
    {
        int i, j, k = 0;
        for (i = 1; i <= n; i++) // row=6
        {
            // Print spaces
            for (j = i; j < n; j++) {
                System.out.print(" ");
            }
            // Print #
            while (k != (2 * i - 1)) {
                if (k == 0 || k == 2 * i - 2)
                    System.out.print("#");
                else
                    System.out.print(" ");
                k++;
                ;
            }
            k = 0;

            // print next row
            System.out.println();
        }
        // print last row
        for (i = 0; i < 2 * n - 1; i++) {
            System.out.print("#");
        }
    }
}

/*This code is contributed by Nikita Tiwari.*/

Python

# Python program to print a hollow
# pyramid pattern

def printPattern( n) :
    k = 0
    for i in range(1,n+1) : #row 6

        # Print spaces
        for j in range(i,n) :
            print(' ', end='')

        # Print #
        while (k != (2 * i - 1)) :
            if (k == 0 or k == 2 * i - 2) :
                print('#', end='')
            else :
                print(' ', end ='')
            k = k + 1
        k = 0;
        print ("") # print next row

    # print last row
    for i in range(0, 2 * n -1) :
        print ('#', end = '')

# Driver code
n = 6
printPattern(n)

# This code is contributed by Nikita Tiwari.

C#

using System;
public class GFG{

    public static void Main()
    {
        int n = 6;
        printPattern(n);
    }

    static void printPattern(int n)
    {
        int i, j, k = 0;
        for (i = 1; i <= n; i++) // row=6
        {
            // Print spaces
            for (j = i; j < n; j++) {
                Console.Write(" ");
            }
            // Print #
            while (k != (2 * i - 1)) {
                if (k == 0 || k == 2 * i - 2)
                    Console.Write("#");
                else
                    Console.Write(" ");
                k++;
                ;
            }
            k = 0;

            // print next row
            Console.WriteLine();
        }
        // print last row
        for (i = 0; i < 2 * n - 1; i++) {
            Console.Write("#");
        }
    }
}

// This code is contributed by laxmigangarajula03

PHP

<?php
// php program to print a
// hollow pyramid pattern

function printPattern($n)
{
    $k = 0;

    // row=6
    for ($i = 1; $i <= $n; $i++)
    {

        // Print spaces
        for ($j = $i; $j < $n; $j++)
        {
            echo " ";
        }

        // Print #
        while ($k != (2 * $i - 1))
        {
            if ($k == 0 || $k == 2 *
                             $i - 2)
                echo "#";
            else
                echo " ";
            $k++;
        }
        $k = 0;

        // print next row
        echo "\n";
    }

    // print last row
    for ($i = 0; $i < 2 * $n - 1; $i++)
    {
        echo "#";
    }
}

//Driver Code
$n = 6;
printPattern($n);

// This code is contributed by mits
?>

Javascript

<script>
      // JavaScript program to print a hollow pyramid pattern
      var n = 6;
      printPattern(n);
      function printPattern(n)
      {
        var i, j, k = 0;
        for (i = 1; i <= n; i++)// row=6
        {
          // Print spaces
          for (j = i; j < n; j++)
          {
            document.write("  ");
          }

          // Print #
          while (k != 2 * i - 1)
          {
            if (k == 0 || k == 2 * i - 2)
                document.write("#");
            else
                document.write("  ");
            k++;
          }
          k = 0;
          document.write("<br>"); // print next row
        }

        // print last row
        for (i = 0; i < 2 * n - 1; i++)
        {
          document.write("#");
        }
      }

      // This code is contributed by rdtank.
    </script>

Output

     #
    # #
   #   #
  #     #
 #       #
#         #
###########

2. Hollow Diamond

Note: For even input, print the pattern for n-1.

Example:

Input: 1

Output:

For n=1

Input: 7

Output:

For n=7

Input: 9

Output:

For n=9

Approach: To print diamond we need to print spaces before star and after the star to achieve constant increasing distance of stars.

To print the box shape we need to print ‘-‘ for i==1 (first row) & i==n (last row) and ‘|’ for j==1 (first column) and j==n (last column).

Algorithm: 1. If n is odd increment n.

2. Find mid=n/2.

3. Traverse from 1 to mid to print upper half of the pattern (say i).

4. Traverse from 1 to mid-i to print spaces for upper left most outer box (say j).

5. If (i==1) print ‘*’ (since for first row we need only one star).

6. else print ‘*’ and traverse from 1 to 2*i-3 to print spaces for hollow diamond (say j) and print ‘*’ after loop is over.

7. Traverse from 1 to mid-i to print spaces again for upper right most outer box (say j).

8. Close the loop at step 3.

9. Traverse from mid+1 to n-1 to print lower half of the pattern (say i).

4. Traverse from 1 to i-mid to print spaces for lower left most outer box (say j).

5. If (i==n-1) print ‘*’ (since for last row we need only one star).

6. else print ‘*’ and traverse from 1 to 2*(n-i)-3 to print spaces for hollow diamond (say j) and print ‘*’ after loop is over.

7. Traverse from 1 to i-mid to print spaces again for lower right most outer box (say j).

8. Close the loop at step 9.

C++14

#include <bits/stdc++.h>
using namespace std;

// function to print the pattern
void printPattern(int& n)
{
    int i,j,mid;
    if(n%2==1) //when n is odd, increase it by 1 to make it even
      n++;
    mid = n/2;

    // upper half pattern
    for(i = 1; i<= mid; i++) {
      for(j = 1; j<=mid-i; j++) //print the blank spaces and outer box before star
         cout<<" ";

      if(i == 1) {
         cout << "*";
      }else{
         cout << "*"; //in each line star at start and end position
         for(j = 1; j<=2*i-3; j++) { //print space to make hollow
            cout << " ";
         }
         cout << "*";
      }
      for(j = 1; j<=mid-i; j++) //print the blank spaces and outer box after star
         cout<<" ";

      cout << endl;
   }

   // lower half pattern
   for(i = mid+1; i<n; i++) {

      for(j = 1; j<=i-mid; j++) //print the blank spaces and outer box before star
         cout<<" ";

      if(i == n-1) {
         cout << "*";
      }else{
         cout << "*"; //in each line star at start and end position
         for(j = 1; j<=2*(n - i)-3; j++) { //print space to make hollow
            cout << " ";
         }
         cout << "*";
      }
      for(j = 1; j<=i-mid; j++) //print the blank spaces and outer box after star
         cout<<" ";

      cout << endl;
   }
}

// driver's code
int main() {
   int n=7;
   printPattern(n);
}
// this code is contributed by prophet1999

Java

// JAVA program
class GFG{

// function to print the pattern
static void printPattern(int n)
{
    int i,j,mid;
    if(n%2==1) //when n is odd, increase it by 1 to make it even
      n++;
    mid = n/2;

    // upper half pattern
    for(i = 1; i<= mid; i++) {
      for(j = 1; j<=mid-i; j++) //print the blank spaces and outer box before star
         System.out.print(" ");

      if(i == 1) {
         System.out.print("*");
      }else{
         System.out.print("*"); //in each line star at start and end position
         for(j = 1; j<=2*i-3; j++) { //print space to make hollow
            System.out.print(" ");
         }
         System.out.print("*");
      }
      for(j = 1; j<=mid-i; j++) //print the blank spaces and outer box after star
         System.out.print(" ");

      System.out.println();
   }

   // lower half pattern
   for(i = mid+1; i<n; i++) {

      for(j = 1; j<=i-mid; j++) //print the blank spaces and outer box before star
         System.out.print(" ");

      if(i == n-1) {
         System.out.print("*");
      }else{
         System.out.print("*"); //in each line star at start and end position
         for(j = 1; j<=2*(n - i)-3; j++) { //print space to make hollow
            System.out.print(" ");
         }
         System.out.print("*");
      }
      for(j = 1; j<=i-mid; j++) //print the blank spaces and outer box after star
         System.out.print(" ");

      System.out.println();
   }

}

    // driver's code
    public static void main(String args[])
    {
        int n = 7;
        printPattern(n);
    }
}

// This code is contributed by Pushpesh Raj.

C#

// C# program
using System;
public class GFG{

  // function to print the pattern
  public static void printPattern(int n)
  {
    int i, j, mid;
    if(n % 2 == 1) //when n is odd, increase it by 1 to make it even
      n++;
    mid = n/2;

    // upper half pattern
    for(i = 1; i <= mid; i++) {
      for(j = 1; j <= mid - i; j++) //print the blank spaces and outer box before star
        Console.Write(" ");

      if(i == 1) {
        Console.Write("*");
      }else{
        Console.Write("*"); //in each line star at start and end position
        for(j = 1; j <= 2 * i - 3; j++) { //print space to make hollow
          Console.Write(" ");
        }
        Console.Write("*");
      }
      for(j = 1; j <= mid - i; j++) //print the blank spaces and outer box after star
        Console.Write(" ");

      Console.WriteLine();
    }

    // lower half pattern
    for(i = mid + 1; i < n; i++) {

      for(j = 1; j <= i - mid; j++) //print the blank spaces and outer box before star
        Console.Write(" ");

      if(i == n - 1) {
        Console.Write("*");
      }else{
        Console.Write("*"); //in each line star at start and end position
        for(j = 1; j <= 2*(n - i)-3; j++) { //print space to make hollow
          Console.Write(" ");
        }
        Console.Write("*");
      }
      for(j = 1; j<=i-mid; j++) //print the blank spaces and outer box after star
        Console.Write(" ");

      Console.WriteLine();
    }

  }

  // driver's code
  public static void Main()
  {
    int n = 7;
    printPattern(n);
  }
}

// This code is contributed by Aman Kumar.

Output

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

Time Complexity: O(n^2) for given input n

Auxiliary Space: O(1)

3. Hollow Diamond bounded inside a rectangular box made of horizontal and vertical dashes(-).

Write a program to Print hollow diamond pattern bound inside a box made of dash(-) and bitwise-OR(|) as shown below.

Note: For even input, print the pattern for n-1.

Example:

Input: 1

Output:

For n=1

Input: 7

Output:

For n=7

Input: 9

Output:

For n=9

Approach: To print diamond we need to print spaces before star and after the star to achieve constant increasing distance of stars.

To print the box shape we need to print ‘-‘ for i==1 (first row) & i==n (last row) and ‘|’ for j==1 (first column) and j==n (last column).

Algorithm: 1. If n is odd increment n.

2. Find mid=n/2.

3. Traverse from 1 to mid to print upper half of the pattern (say i).

4. Traverse from 1 to mid-i to print upper left most outer box (say j).

5. If (i==1) print ‘*’ (since for first row we need only one star).

6. else print ‘*’ and traverse from 1 to 2*i-3 to print spaces for hollow diamond (say j) and print ‘*’ after loop is over.

7. Traverse from 1 to mid-i to print upper right most outer box (say j).

8. Close the loop at step 3.

9. Traverse from mid+1 to n-1 to print lower half of the pattern (say i).

4. Traverse from 1 to i-mid to print lower left most outer box (say j).

5. If (i==n-1) print ‘*’ (since for last row we need only one star).

6. else print ‘*’ and traverse from 1 to 2*(n-i)-3 to print spaces for hollow diamond (say j) and print ‘*’ after loop is over.

7. Traverse from 1 to i-mid to print lower right most outer box (say j).

8. Close the loop at step 9.

C++14

#include <bits/stdc++.h>
using namespace std;

// function to print the pattern
void printPattern(int& n)
{
    int i,j,mid;
    if(n%2==1) //when n is odd, increase it by 1 to make it even
      n++;
    mid = n/2;

    // upper half pattern
    for(i = 1; i<= mid; i++) {
      for(j = 1; j<=mid-i; j++) { //print the blank spaces and outer box before star
         if(i==1)
         cout<<"-";
         else if(j==1)
         cout << "|";
         else cout<<" ";
      }
      if(i == 1) {
         cout << "*";
      }else{
         cout << "*"; //in each line star at start and end position
         for(j = 1; j<=2*i-3; j++) { //print space to make hollow
            cout << " ";
         }
         cout << "*";
      }
      for(j = 1; j<=mid-i; j++) { //print the blank spaces and outer box after star
         if(i==1)
         cout<<"-";
         else if(j==mid-i)
         cout << "|";
         else cout<<" ";
      }
      cout << endl;
   }

   // lower half pattern
   for(i = mid+1; i<n; i++) {

      for(j = 1; j<=i-mid; j++) { //print the blank spaces and outer box before star
         if(i==n-1)
         cout<<"-";
         else if(j==1)
         cout << "|";
         else cout<<" ";
      }
      if(i == n-1) {
         cout << "*";
      }else{
         cout << "*"; //in each line star at start and end position
         for(j = 1; j<=2*(n - i)-3; j++) { //print space to make hollow
            cout << " ";
         }
         cout << "*";
      }
      for(j = 1; j<=i-mid; j++) { //print the blank spaces and outer box after star
         if(i==n-1)
         cout<<"-";
         else if(j==i-mid)
         cout << "|";
         else cout<<" ";
      }
      cout << endl;
   }
}

// driver's code
int main() {
   int n=12;
   printPattern(n);
}
// this code is contributed by prophet1999

Java

// Java code to implement the above approach

import java.io.*;
import java.util.*;

class GFG
{
  // function to print the pattern
  public static void printPattern(int n)
  {
      int i,j,mid;
      if(n%2==1) //when n is odd, increase it by 1 to make it even
      n++;
      mid = n/2;

      // upper half pattern
      for(i = 1; i<= mid; i++) {
          for(j = 1; j<=mid-i; j++) { //print the blank spaces and outer box before star
          if(i==1)
          System.out.print("-");
          else if(j==1)
          System.out.print("|");
          else
          System.out.print(" ");
          }

      if(i == 1) {
         System.out.print("*");
      }
      else{
         System.out.print("*"); //in each line star at start and end position
         for(j = 1; j<=2*i-3; j++) { //print space to make hollow
            System.out.print(" ");
         }
         System.out.print("*");
      }
      for(j = 1; j<=mid-i; j++) { //print the blank spaces and outer box after star
         if(i==1)
         System.out.print("-");
         else if(j==mid-i)
         System.out.print("|");
         else System.out.print(" ");
      }
      System.out.print("\n");
   }

   // lower half pattern
   for(i = mid+1; i<n; i++) {

      for(j = 1; j<=i-mid; j++) { //print the blank spaces and outer box before star
         if(i==n-1)
         System.out.print("-");
         else if(j==1)
         System.out.print("|");
         else System.out.print(" ");
      }
      if(i == n-1) {
         System.out.print("*");
      }else{
         System.out.print("*"); //in each line star at start and end position
         for(j = 1; j<=2*(n - i)-3; j++) { //print space to make hollow
            System.out.print(" ");
         }
         System.out.print("*");
      }
      for(j = 1; j<=i-mid; j++) { //print the blank spaces and outer box after star
         if(i==n-1)
         System.out.print("-");
         else if(j==i-mid)
         System.out.print("|");
         else System.out.print(" ");
      }
      System.out.print("\n");
   }
  }

  // Driver Code
  public static void main(String[] args)
  {
    int n=12;
    printPattern(n);
  }
}

//this code is contributed by adityapatil12

Output

-----*-----
|   * *   |
|  *   *  |
| *     * |
|*       *|
*         *
|*       *|
| *     * |
|  *   *  |
|   * *   |
-----*-----

Time Complexity: O(n*n)

Auxiliary Space: O(1)

This article is contributed by Shivani Ghughtyal and improved by Himanshu Patel(@prophet1999). If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
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