The Butterfly Star Pattern (Combining Triangles)

The Ultimate Composite Test

The Butterfly pattern is often the final boss of university pattern exams. It looks like an intricate mirrored web of stars and spaces. If N = 3 (half height):

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

Deconstructing the Butterfly

Just like the Diamond, split the problem in half horizontally. The top half consists of 3 distinct sections per row:

1. A left-aligned right triangle (Stars).
2. A large block of hollow space (Spaces).
3. A right-aligned right triangle (Stars).

The Math (Top Half)

For any row in the top half (where n = 3):

• Left Stars: Exactly equal to the row number.
• Spaces: The space in the middle is mathematically 2 * (N - row).
• Right Stars: Exactly equal to the row number.

The Implementation

int n = 3;
// Top Half
for (int row = 1; row <= n; row++) {
    // 1. Left Stars
    for (int i = 1; i <= row; i++) print("*");
    
    // 2. Middle Spaces
    for (int i = 1; i <= 2 * (n - row); i++) print(" ");
    
    // 3. Right Stars
    for (int i = 1; i <= row; i++) print("*");
    
    println();
}

// Bottom Half (Exact same, just reverse the outer loop)
for (int row = n - 1; row >= 1; row--) {
    for (int i = 1; i <= row; i++) print("*");
    for (int i = 1; i <= 2 * (n - row); i++) print(" ");
    for (int i = 1; i <= row; i++) print("*");
    println();
}

The Takeaway

Never panic when presented with a complex visual problem. Break it into vertical chunks (left, middle, right) and horizontal chunks (top half, bottom half). Constructing the Butterfly pattern proves you can string together multiple mathematical boundaries flawlessly.