Pattern N, eee, PPPPP using unformatted I/O

Only putchar() is used for output (unformatted), row r contains 2r - 1 copies of one letter, and each row is preceded by blanks to make a triangle.

#include <stdio.h>
int main(void)
{
    char letters[] = {'N', 'e', 'P', 'a', 'L'};
    int row, k;
    for (row = 1; row <= 5; row++)
    {
        for (k = 1; k <= 5 - row; k++)      /* leading blanks */
        {
            putchar(' ');
            putchar(' ');
        }
        for (k = 1; k <= 2 * row - 1; k++)  /* letter and a space */
        {
            putchar(letters[row - 1]);
            putchar(' ');
        }
        putchar('\n');
    }
    return 0;
}

Output:

        N 
      e e e 
    P P P P P 
  a a a a a a a 
L L L L L L L L L

Explanation

• The outer loop runs once per row (5 rows) and picks the letter from the array.
• The first inner loop prints 5 - row pairs of blanks, which shifts the row to the right.
• The second inner loop prints 2*row - 1 letters, each followed by a blank.
• The number of letters in the rows is 1, 3, 5, 7, 9.