题解 | #回型矩阵#

#include <stdio.h>
int main() {
	int n = 0;
	int i = 0;
	int j = 0;
	int num = 1;//用来赋值的数
	int arr[20][20] = { 0 };
	int begin = 0;//给数组赋值开始下标
	int end = 0;//给数组赋值结束下标
	scanf("%d", &n);
	begin = 0;
	end = n - 1;
	while (num-1 <= n * n)//每一次赋值最外面的一圈
	{
		for (i = begin; i < end; i++)//每一回赋值(end-begin)个数
		{
			arr[begin][i] = num + i - (n - 1 - end);
			arr[i][end] = num + (end-begin) + i - (n - 1 - end);
			arr[end][end - (i - (n - 1 - end))] = num + 2 * (end - begin)+i-(n-1-end);
			arr[end - (i - (n - 1 - end))][begin] = num + 3 * (end - begin)+i-(n-1-end);
		}
		num += 4 * (end - begin);
		begin++;
		end--;
	}
	if (n % 2 == 1)
	{
		arr[n / 2][n / 2] = n * n;
	}
	for (i = 0; i < n; i++)
	{
		for (j = 0; j < n; j++)
		{
			printf("%d ", arr[i][j]);
		}
		printf("\n");
	}
	return 0;
}