Subsets#3950
Imagine you are a teacher with problems, and you need to organize a contest using these problems. To determine the best combination, you decide to list all possible subsets of problems. Remember, the contest must include at least one problem.
You are given a single integer (1 \le N \le 10).
Output all possible subsets of the set \{1, 2, \ldots, N\}. Each line should represent one subset. Start with the number of problems in the subset, followed by the problem numbers included in that subset.
Example 1