题解 | #回型矩阵#

/* BC133 回型矩阵 */
#include <stdio.h>

int main() {
    int n = 0;
    int array[20][20] = { 0 };

    scanf("%d", &n);
    int num = 1;
    int lmargin = 0;
    int rmargin = n - 1;
    int count = 1;

    int row = 0, col = 0;
    while (lmargin <= rmargin)
    {
        while (col <= rmargin)                      //左上角->右上角
            array[row][col++] = num++;
        count++, col--, row++;

        while (row <= rmargin)                      //右上角->右下角
            array[row++][col] = num++;
        count++, row--, col--;

        while (col >= lmargin)                      //右下角->左下角
            array[row][col--] = num++;
        count++, col++, row--;

        if (count == 4)                             //改变边界
            lmargin++, rmargin--, count = 0;

        while (row >= lmargin)
            array[row--][col] = num++;              //左下角->左上角
        count++, row++, col++;
    }

    for (row = 0; row < n; row++)
    {
        for (col = 0; col < n; col++)
        {
            printf("%d ", array[row][col]);
        }
        printf("\n");
    }

    return 0;
}