Program to print hollow pyramid and diamond pattern

Difficulty Level : Medium
Last Updated : 10 Sep, 2021

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 ‘#’ characters by space character and we will 2*N-1 (N = number of rows in pattern) ‘#’ characters in last row.
Examples:

Input rows: 6
Output:
     #
    # #
   #   #
  #     #
 #       #
#         #
###########

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C++

// 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 << "#";
    }
}

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.

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:

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

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Program to print hollow pyramid and diamond pattern

C++

Java

Python

PHP

Javascript