Example: Generate Spiral Matrix

// Generate Spiral Matrix
#include <stdio.h>

// Function to print the matrix
void printMatrix(int N, int matrix[N][N]) {
    printf("Generated Spiral Matrix:\n");
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            printf("%4d", matrix[i][j]); // Print with spacing for alignment
        }
        printf("\n");
    }
}

int main() {
    // Step 1: Define matrix size N
    int N;
    printf("Enter the size of the square matrix (N): ");
    scanf("%d", &N);

    // Step 2: Declare the N x N matrix
    int matrix[N][N];

    // Step 3: Initialize boundary pointers and current number
    int top = 0, bottom = N - 1;
    int left = 0, right = N - 1;
    int currentNum = 1; // Start filling from 1

    // Step 4: Loop until all elements are filled (boundaries cross)
    while (top <= bottom && left <= right) {
        // Fill from left to right along the top row
        for (int i = left; i <= right; i++) {
            matrix[top][i] = currentNum++;
        }
        top++; // Move top boundary down

        // Fill from top to bottom along the right column
        for (int i = top; i <= bottom; i++) {
            matrix[i][right] = currentNum++;
        }
        right--; // Move right boundary left

        // Check if top boundary is still less than or equal to bottom boundary
        // This is crucial for non-square matrices, though here N x N
        // It prevents re-traversing if only a single row or column is left
        if (top <= bottom) {
            // Fill from right to left along the bottom row
            for (int i = right; i >= left; i--) {
                matrix[bottom][i] = currentNum++;
            }
            bottom--; // Move bottom boundary up
        }

        // Check if left boundary is still less than or equal to right boundary
        // Similar to the check for top <= bottom
        if (left <= right) {
            // Fill from bottom to top along the left column
            for (int i = bottom; i >= top; i--) {
                matrix[i][left] = currentNum++;
            }
            left++; // Move left boundary right
        }
    }

    // Step 5: Print the generated matrix
    printMatrix(N, matrix);

    return 0;
}