Hour-glass Pattern

Given positive integer n, print numeric pattern in form of an hourglass.
Examples :

Input : rows_no = 7
Output :

1 2 3 4 5 6 7
 2 3 4 5 6 7
  3 4 5 6 7
   4 5 6 7
    5 6 7
     6 7 
      7
     6 7
    5 6 7
   4 5 6 7
  3 4 5 6 7
 2 3 4 5 6 7
1 2 3 4 5 6 7

C++

// CPP code for hour glass
// pattern.
#include <iostream>
using namespace std;

// Function definition
void pattern(int rows_no)
{
    int i, j, k;

    // for loop for printing
    // upper half
    for (i = 1; i <= rows_no; i++) {

        // printing i spaces at
        // the beginning of each row
        for (k = 1; k < i; k++)
            cout << " ";

        // printing i to rows value
        // at the end of each row
        for (j = i; j <= rows_no; j++)
            cout << j << " ";

        cout << endl;
    }

    // for loop for printing lower half
    for (i = rows_no - 1; i >= 1; i--) {

        // printing i spaces at the
        // beginning of each row
        for (k = 1; k < i; k++)
            cout << " ";


        // printing i to rows value
        // at the end of each row
        for (j = i; j <= rows_no; j++)
            cout << j << " ";

        cout << endl;
    }
}

// Driver code
int main()
{
    // taking rows value from the user
    int rows_no = 7;

    pattern(rows_no);
    return 0;
}

Java

// Java code for hour glass
// pattern.
import java.io.*;

class GFG
{
    // Function definition
    static void pattern(int rows_no)
    {
        int i, j, k;

        // for loop for printing
        // upper half
        for (i = 1; i <= rows_no; i++) {

            // printing i spaces at
            // the beginning of each row
            for (k = 1; k < i; k++)
                System.out.print(" ");

            // printing i to rows value
            // at the end of each row
            for (j = i; j <= rows_no; j++)
                System.out.print(j + " ");

            System.out.println();
        }

        // for loop for printing lower half
        for (i = rows_no - 1; i >= 1; i--)
        {
            // printing i spaces at the
            // beginning of each row
            for (k = 1; k < i; k++)
                System.out.print(" ");

            // printing i to rows value
            // at the end of each row
            for (j = i; j <= rows_no; j++)
                System.out.print(j + " ");

            System.out.println();
        }
    }

    // Driver code
    public static void main (String[] args)
    {
        // taking rows value from the user
        int rows_no = 7;

        pattern(rows_no);

    }
}

// This code is contributed by vt_m.

Python3

# Python3 code for hour glass pattern

# Function definition
def pattern(rows_no):

    # for loop for printing upper half
    for i in range(1, rows_no + 1):

        # printing i spaces at the
        # beginning of each row
        for k in range(1, i):
            print(" ", end = "")

        # printing i to rows value
        # at the end of each row
        for j in range(i, rows_no + 1):
            print(j, end = " ")

        print()

    # for loop for printing lower half
    for i in range(rows_no - 1, 0, -1):

        # printing i spaces at the
        # beginning of each row
        for k in range(1, i):
            print(" ", end = "")

        # printing i to rows value
        # at the end of each row
        for j in range(i, rows_no + 1):
            print(j, end = " ")

        print()

# Driver code

# taking rows value from the user
rows_no = 7

pattern(rows_no)

# This code is contributed
# by ihritik

C#

// C# code for hour glass
// pattern.
using System;
class GFG
{
    // Function definition
    static void pattern(int rows_no)
    {
        int i, j, k;

        // for loop for printing
        // upper half
        for (i = 1; i <= rows_no; i++) {

            // printing i spaces at
            // the beginning of each row
            for (k = 1; k < i; k++)
                Console.Write(" ");

            // printing i to rows value
            // at the end of each row
            for (j = i; j <= rows_no; j++)
                Console.Write(j + " ");

            Console.WriteLine();
        }

        // for loop for printing lower half
        for (i = rows_no - 1; i >= 1; i--)
        {
            // printing i spaces at the
            // beginning of each row
            for (k = 1; k < i; k++)
                Console.Write(" ");

            // printing i to rows value
            // at the end of each row
            for (j = i; j <= rows_no; j++)
                Console.Write(j + " ");

            Console.WriteLine();
        }
    }

    // Driver code
    public static void Main ()
    {
        // taking rows value from the user
        int rows_no = 7;

        pattern(rows_no);

    }
}

// This code is contributed by vt_m.

PHP

<?php
// PHP code for hour glass pattern
// Function definition
function pattern($rows_no)
{
    // for loop for printing
    // upper half
    for ($i = 1; $i <= $rows_no; $i++)
    {

        // printing i spaces at
        // the beginning of each row
        for ($k = 1; $k < $i; $k++)
            echo " ";

        // printing i to rows value
        // at the end of each row
        for ($j = $i; $j <= $rows_no; $j++)
            echo $j." ";

        echo "\n";
    }

    // for loop for printing lower half
    for ($i = $rows_no - 1; $i >= 1; $i--)
    {

        // printing i spaces at the
        // beginning of each row
        for ($k = 1; $k < $i; $k++)
            echo " ";

        // printing i to rows value
        // at the end of each row
        for ($j = $i; $j <= $rows_no; $j++)
            echo $j." ";

        echo "\n";
    }
}

// Driver code
$rows_no = 7;
pattern($rows_no);

// This code is contributed by mits
?>

Javascript

<script>
// Javascript code for hour glass
// pattern.

    // Function definition
    function pattern( rows_no)
    {
        let i, j, k;

        // for loop for printing
        // upper half
        for (i = 1; i <= rows_no; i++)
        {

            // printing i spaces at
            // the beginning of each row
            for (k = 1; k < i; k++)
                document.write(" ");

            // printing i to rows value
            // at the end of each row
            for (j = i; j <= rows_no; j++)
                document.write(j + " ");

            document.write("<br/>");
        }

        // for loop for printing lower half
        for (i = rows_no - 1; i >= 1; i--)
        {

            // printing i spaces at the
            // beginning of each row
            for (k = 1; k < i; k++)
                document.write(" ");

            // printing i to rows value
            // at the end of each row
            for (j = i; j <= rows_no; j++)
                document.write(j + " ");

            document.write("<br/>");
        }
    }

    // Driver code

    // taking rows value from the user
    let rows_no = 7;
    pattern(rows_no);

// This code is contributed by gauravrajput1
</script>

Output :

1 2 3 4 5 6 7
 2 3 4 5 6 7
  3 4 5 6 7
   4 5 6 7
    5 6 7
     6 7 
      7
     6 7
    5 6 7
   4 5 6 7
  3 4 5 6 7
 2 3 4 5 6 7
1 2 3 4 5 6 7

Time Complexity : O(rows_no*rows_no) ,where rows_no is rows value taken from user.

Space Complexity : O(1) ,as we are not using any extra space.