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 then 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 ith line contains following number of star:
    Number of '*' in ith line = i
    
  • Lower Half: The lower half of the pattern contains star ‘*’ in decreasing order where ith line contains following number of star:
    Number of '*' in ith line = N - i
    
  • Below is the implementation of the above approach:

    C++

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    // 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);
    }

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    Java

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    // 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

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    Python3

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    # 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

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    C#

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    // 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

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    Output:

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

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    Improved By : Rohit_ranjan, skylags