Diamond pattern printing using numbers | Diamond number patterns | FACE Prep

Introduction

Pattern printing is an essential topic in programming, commonly asked in interviews and competitive coding challenges. Among these, diamond patterns using numbers are both visually appealing and a great way to test logic-building skills.

This guide covers different diamond-based number patterns, their logic, and optimized code implementations in C, C++, Java, and Python.

What You’ll Learn:

• Half-Diamond Pattern using Numbers
• Half-Diamond Pattern using Numbers and Stars
• Full-Diamond Pattern using Numbers and Stars
• Code Implementations in Multiple Languages
• Suggested Visuals for Better Understanding

Pattern 1: Half-Diamond Pattern Using Numbers

Example Input & Output

Input:
3 4

Output:

3  
44  
555  
6666  
555  
44  
3  

Logic Behind the Pattern

• The first half of the pattern increases in both rows and digit repetition.
• The second half mirrors the first half in reverse order.
• Numbers increase from input value N downwards.

Code Implementation

C Program

#include <stdio.h>

void printHalfDiamond(int n) {
    for (int i = 0; i < n; i++) {
        for (int j = 0; j <= i; j++)
            printf("%d", n + i);
        printf("\n");
    }
    for (int i = n - 2; i >= 0; i--) {
        for (int j = 0; j <= i; j++)
            printf("%d", n + i);
        printf("\n");
    }
}

int main() {
    int num;
    printf("Enter a number: ");
    scanf("%d", &num);
    printHalfDiamond(num);
    return 0;
}

Python Program

def print_half_diamond(n):
    for i in range(n):
        print(str(n + i) * (i + 1))
    for i in range(n - 2, -1, -1):
        print(str(n + i) * (i + 1))

num = int(input("Enter a number: "))
print_half_diamond(num)

Optimization: Using str * n for easy pattern printing.

Pattern 2: Half-Diamond Using Numbers and Stars

Example Input & Output

Input:
4

Output:

1  
2*2  
3*3*3  
4*4*4*4  
4*4*4*4  
3*3*3  
2*2  
1  

Logic Behind the Pattern

• The pattern follows a diamond shape using numbers and stars (*).
• Numbers appear increasingly from 1 to N in both upper and lower halves.

Code Implementation

C++ Program

#include <iostream>
using namespace std;

void printPattern(int n) {
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= i; j++) {
            cout << i;
            if (j < i) cout << "*";
        }
        cout << endl;
    }
    for (int i = n; i >= 1; i--) {
        for (int j = 1; j <= i; j++) {
            cout << i;
            if (j < i) cout << "*";
        }
        cout << endl;
    }
}

int main() {
    int num;
    cout << "Enter a number: ";
    cin >> num;
    printPattern(num);
    return 0;
}

Python Program

def print_half_diamond_star(n):
    for i in range(1, n + 1):
        print('*'.join([str(i)] * i))
    for i in range(n, 0, -1):
        print('*'.join([str(i)] * i))

num = int(input("Enter a number: "))
print_half_diamond_star(num)

Optimization: '*'.join(list) to format output efficiently.

Pattern 3: Full-Diamond Using Numbers & Stars

Example Input & Output

Input:
4

Output:

1  
2*3  
4*5*6  
7*8*9*10  
7*8*9*10  
4*5*6  
2*3  
1  

Logic Behind the Pattern

• Numbers increase consecutively instead of being repeated.
• The upper half starts from 1, while the lower half mirrors the top.
• Each row starts where the previous row ended.

Code Implementation

Java Program

import java.util.Scanner;

public class DiamondPattern {
    static void printDiamond(int n) {
        int num = 1;
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(num);
                if (j < i) System.out.print("*");
                num++;
            }
            System.out.println();
        }
        num -= n;
        for (int i = n; i >= 1; i--) {
            for (int j = 1; j <= i; j++) {
                System.out.print(num);
                if (j < i) System.out.print("*");
                num++;
            }
            System.out.println();
            num -= (i - 1);
        }
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a number: ");
        int num = sc.nextInt();
        printDiamond(num);
        sc.close();
    }
}

Python Program

def print_diamond(n):
    num = 1
    for i in range(1, n + 1):
        print('*'.join(str(num + j) for j in range(i)))
        num += i
    num -= n
    for i in range(n, 0, -1):
        print('*'.join(str(num + j) for j in range(i)))
        num -= (i - 1)

num = int(input("Enter a number: "))
print_diamond(num)

Optimization: Using Python’s list comprehension for efficient joining.

Conclusion

Diamond pattern printing is a great exercise to enhance looping concepts and problem-solving skills. This guide provided three different number-based diamond patterns with optimized code in C, C++, Java, and Python.