C Program to Print Floyd’s Triangle Pyramid Patterns

Here we will build a C program to print Floyd’s Triangle Pyramid pattern. Floyd’s Triangle is a triangular array of natural numbers where the n^th row contains n elements. There are 8 methods to cover all variations of Floyd’s Triangles

1. Floyd’s triangle using for loop.
2. Floyd’s triangle using while loop.
3. Floyd’s triangle using recursion.
4. Reverse Floyd’s triangle using for loop.
5. Star Floyd’s triangle using for loop.
6. Alphabets Floyd’s triangle using for loop.

Floyd’s Triangle of natural numbers

1
2 3
4 5    6
7 8 9 10
11 12 13 14 15

Floyd’s triangle of alphabets

a
b c
d e f
g h i j

Star Floyd pattern

*
* *
* * *
* * * *

1. Floyd’s triangle using for loop

C

// C program to Demonstrate Floyd's Triangle
// Using for loop
#include <stdio.h>
void floyd(int n)
{
    int i, j = 1;

    // Condition printing the number of element
    for (i = 1; i <= (n * (n + 1)) / 2; i++) {

        printf("%d ", i);

        // condition for row of number of element printing
        if (i == (j * (j + 1)) / 2) {
            printf("\n");
            j++;
        }
    }
}
int main() { floyd(6); }

Output:

1 
2 3 
4 5 6 
7 8 9 10 
11 12 13 14 15 
16 17 18 19 20 21 

Time Complexity: O(n²)

Auxiliary Space: O(1)

2. Floyd’s triangle using while loop

C

// C program to Demonstrate Floyd's Triangle
// Using while loop
#include <stdio.h>
void floyd(int n)
{
    int i = 1, j = 1;
    // condition for number of element
    while (i <= (n * (n + 1)) / 2) {

        printf("%d ", i);

        // condition for what element has to print and
        // how many times
        if (i == (j * (j + 1)) / 2) {
            printf("\n");
            j++;
        }
        i++;
    }
}
int main() { floyd(6); }

Output:

1 
2 3 
4 5 6 
7 8 9 10 
11 12 13 14 15 
16 17 18 19 20 21 

Time Complexity: O(n²)

Auxiliary Space: O(1)

3. Floyd’s triangle using recursion

C

// C program to Demonstrate Floyd's Triangle
// Using recursion
#include <stdio.h>
int row = 1, i = 1;
void floyd(int n)
{
    // base condition
    if (n == 0)
        return;

    for (int j = 1; j <= row; j++)
        printf("%d ", i++);
    row++;
    printf("\n");
    floyd(n - 1);
}
int main() { floyd(6); }

Output:

1 
2 3 
4 5 6 
7 8 9 10 
11 12 13 14 15 
16 17 18 19 20 21 

Time Complexity: O(n²)

Auxiliary Space: O(n) for call stack, because using recursion

4. Reverse Floyd’s triangle using for loop

C++

// C program to Demonstrate Reverse Floyd's
// Triangle Using for loop
#include <iostream>
using namespace std;

void reverse_floyd(int n)
{
    // total number of elements
    int i = n * (n + 1) / 2;

    // condition for printing them
    while (i > 0) {
        for (int j = 0; j < n; j++)
            printf("%d ", i--);
        n--;
        printf("\n");
    }
}
int main()
{
    reverse_floyd(6);
    return 0;
}

Output:

21 20 19 18 17 16 
15 14 13 12 11 
10 9 8 7 
6 5 4 
3 2 
1 

Time Complexity: O(n²)

Auxiliary Space: O(1)

5. Star Floyd’s triangle using for loop

C++

// C program to Demonstrate Star Floyd's
// Triangle Using for loop
#include <stdio.h>
void floyd(int n)
{
    int i, j = 1;
    for (i = 1; i <= (n * (n + 1)) / 2; i++) {
        printf("* ");
        if (i == (j * (j + 1)) / 2) {
            printf("\n");
            j++;
        }
    }
}
int main() { floyd(6); }

Output:

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

Time Complexity: O(n²)

Auxiliary Space: O(1)

6. Alphabets Floyd’s triangle using for loop

C

// C program to Demonstrate Alphabet Floyd's
// Triangle Using for loop
#include <stdio.h>

void alpha_floyd(int n)
{
    int k = 'a';
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= i; j++)
            printf("%c ", k++);
        printf("\n");
    }
}
int main()
{

    alpha_floyd(6);
    return 0;
}

Output:

a 
b c 
d e f 
g h i j 
k l m n o 
p q r s t u 

Time Complexity: O(n²)

Auxiliary Space: O(1)