gistfile1.c

#include <stdio.h>
#include <math.h>
#include <stdlib.h>

int main(void)
{
	int size = 0;
	int x, y, step;
	int value = 0;
	int stepCount = 0;
	int *matrix;

	//size = 10;


	printf("Enter size: ");
	scanf("%d", &size);
	printf("\n");

	value = size * size;
	stepCount = size / 2;

	matrix = (int*)malloc(size * size * sizeof(int));

	// main part

	for(step = 0; step < stepCount; ++step)
	{
		//top side
		for(y = 0 + step; y < size - step; ++y)
			matrix[(0 + step) * size + y] = value--;

		//right side
		for(x = 1 + step; x < size - step; ++x)
			matrix[(x * size) + size - 1 - step] = value--;

		//bottom side
		for(y = size - 2 - step; y >= 0 + step; --y)
			matrix[(size - 1 - step) * size + y] = value--;

		//left size
		for(x = size - 2 - step; x > 0 + step; --x)
			matrix[(x * size) + 0 + step] = value--;
	}

	if(size % 2 == 1)
		matrix[stepCount * size + stepCount] = 1;

	// end main part

	for(x = 0; x < size; ++x, printf("\n"))
		for(y = 0; y < size; ++y)
			printf("%3d ", matrix[x * size + y]);

	free(matrix);

	return 0;
}