Example 1

Example 2

1 <= m <= n <= 3 * 104group.length == beforeItems.length == n-1 <= group[i] <= m - 10 <= beforeItems[i].length <= n - 10 <= beforeItems[i][j] <= n - 1i != beforeItems[i][j]beforeItems[i] does not contain duplicates elements.Example 1

Example 2

1 <= m <= n <= 3 * 104group.length == beforeItems.length == n-1 <= group[i] <= m - 10 <= beforeItems[i].length <= n - 10 <= beforeItems[i][j] <= n - 1i != beforeItems[i][j]beforeItems[i] does not contain duplicates elements.