Pattern 7

The idea

A centred pyramid needs two inner loops per row: one that prints the leading spaces and one that prints the stars. Row i gets n-i spaces then 2i-1 stars, which keeps every row the same total width so the pyramid stays centred.

The trick

• Spaces = n - i, stars = 2i - 1; those two formulas produce every centred pyramid.
• Total width is always 2n - 1, which is what makes the centre line up.