rt,这篇题解代码中两处错误,for (int j = 1; j <= n; j++) 应修改为 for (int j = 1; j <= 4 * n + 1; j++),否则 WA,为错解。
for (int j = 1; j <= n; j++)
for (int j = 1; j <= 4 * n + 1; j++)