Concentric Square Number Pattern In C

🔢 C Program: Concentric Square Number Pattern

#include <stdio.h>

int main() {
    int n;
    printf("Enter the number of layers: ");
    scanf("%d", &n);

    int size = 2 * n - 1;

    for (int i = 0; i < size; i++) {
        for (int j = 0; j < size; j++) {
            int min = i;
            if (j < min) min = j;
            if (size - 1 - i < min) min = size - 1 - i;
            if (size - 1 - j < min) min = size - 1 - j;

            printf("%d ", n - min);
        }
        printf("\n");
    }

    return 0;
}
  

📝 Explanation:

This C program prints a concentric number pattern in the form of a square matrix. Each layer of the square is filled with a decreasing number from the outermost layer to the center.

• Input: The user enters the number of layers (n).
• Matrix size: It is calculated using 2 * n - 1. This ensures we have n layers on each side (top, bottom, left, right).
• Two nested loops: These go through each cell (i, j) of the matrix.
• Finding the minimum distance: We calculate the minimum number of steps required to reach the border from cell (i, j). This is done using 4 comparisons:
  • i → distance from top
  • j → distance from left
  • size - 1 - i → distance from bottom
  • size - 1 - j → distance from right
• Print value: The value to print is n - min which gives the correct number for that concentric layer.

💡 Sample Output:

Enter the number of layers: 4

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