Program to print half Diamond star pattern

Given an integer N, the task is to print half-diamond-star pattern.

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

Examples:

Input: N = 3
Output:
*
**
***
**
*

Input: N = 6
Output:
*
**
***
****
*****
******
*****
****
***
**
*

Approach: The idea is to break the pattern into two halves that is upper half and lower half. Then print them separately with the help of the loops. The key observation for printing the upper half and lower half is described as below:

• Upper half: The upper half of the pattern contains star ‘*’ in increasing order where i^th line contains following number of star:

Number of '*' in ith line = 

• Lower Half: The lower half of the pattern contains star ‘*’ in decreasing order where i^th line contains following number of star:

Number of '*' in ith line = 

C++

// C++ implementation to print the
// half diamond star pattern

#include <iostream>

using namespace std;

// Function to print the
// half diamond star pattern
void halfDiamondStar(int N)
{
    int i, j;

    // Loop to print the upper half
    // diamond pattern
    for (i = 0; i < N; i++) {
        for (j = 0; j < i + 1; j++)
            cout << "*";
        cout << "\n";
    }

    // Loop to print the lower half
    // diamond pattern
    for (i = 1; i < N; i++) {
        for (j = i; j < N; j++)
            cout << "*";
        cout << "\n";
    }
}

// Driver Code
int main()
{
    int N = 5;

    // Function Call
    halfDiamondStar(N);
}

Java

// Java implementation to print the
// half diamond star pattern
import java.util.*;

class GFG{

// Function to print the
// half diamond star pattern
static void halfDiamondStar(int N)
{
    int i, j;

    // Loop to print the upper half
    // diamond pattern
    for (i = 0; i < N; i++)
    {
        for (j = 0; j < i + 1; j++)
            System.out.print("*");
        System.out.print("\n");
    }

    // Loop to print the lower half
    // diamond pattern
    for (i = 1; i < N; i++)
    {
        for (j = i; j < N; j++)
            System.out.print("*");
        System.out.print("\n");
    }
}

// Driver Code
public static void main(String[] args)
{
    int N = 5;

    // Function Call
    halfDiamondStar(N);
}
}

// This code is contributed by Rohit_ranjan

Python3

# Python3 implementation to print the
# half diamond star pattern

# Function to print the
# half diamond star pattern
def halfDiamondStar(N):

    # Loop to print the upper half
    # diamond pattern
    for i in range(N):

        for j in range(0, i + 1):
            print("*", end = "")
        print()

    # Loop to print the lower half
    # diamond pattern
    for i in range(1, N):

        for j in range(i, N):
            print("*", end = "")
        print()

# Driver Code
N = 5;

# Function Call
halfDiamondStar(N);

# This code is contributed by skylags

C#

// C# implementation to print the
// half diamond star pattern
using System;

class GFG{

// Function to print the
// half diamond star pattern
static void halfDiamondStar(int N)
{
    int i, j;

    // Loop to print the upper half
    // diamond pattern
    for(i = 0; i < N; i++)
    {
    for(j = 0; j < i + 1; j++)
        Console.Write("*");
    Console.Write("\n");
    }

    // Loop to print the lower half
    // diamond pattern
    for(i = 1; i < N; i++)
    {
    for(j = i; j < N; j++)
        Console.Write("*");
    Console.Write("\n");
    }
}

// Driver Code
public static void Main(String[] args)
{
    int N = 5;

    // Function Call
    halfDiamondStar(N);
}
}

// This code is contributed by Rohit_ranjan

Javascript

// JavaScript implementation to print the
// half diamond star pattern

// Function to print the
// half diamond star pattern
function halfDiamondStar(N)
{
    let i, j;

    // Loop to print the upper half
    // diamond pattern
    for (i = 0; i < N; i++)
    {
        for (j = 0; j < i + 1; j++)
            console.log("*");
            console.log("<br>");
             console.log("\n");
    }

    // Loop to print the lower half
    // diamond pattern
    for (i = 1; i < N; i++)
    {
        for (j = i; j < N; j++)
            console.log("*");
            console.log("<br>");
        console.log("\n");

    }

}

// Driver Code
    let N = 5;

    // Function Call
    halfDiamondStar(N);

Output

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

Time complexity: O(N²) where N is given integer
Auxiliary Space: O(1)