3680 - Generate Schedule.

Medium

You are given an integer n representing n teams. You are asked to generate a schedule such that:

• Each team plays every other team exactly twice: once at home and once away.

• There is exactly one match per day; the schedule is a list of consecutive days and schedule[i] is the match on day i.

• No team plays on consecutive days.

Return a 2D integer array schedule, where schedule[i][0] represents the home team and schedule[i][1] represents the away team. If multiple schedules meet the conditions, return any one of them.

If no schedule exists that meets the conditions, return an empty array.

Example 1:

Input: n = 3

Output: []

Explanation:

Since each team plays every other team exactly twice, a total of 6 matches need to be played: [0,1],[0,2],[1,2],[1,0],[2,0],[2,1].

It's not possible to create a schedule without at least one team playing consecutive days.

Example 2:

Input: n = 5

Output: [0,1,2,3,0,4,1,2,3,4,0,2,1,3,2,4,0,3,1,4,2,0,3,1,4,0,2,1,4,3,1,0,3,2,4,1,3,0,4,2]

Explanation:

Since each team plays every other team exactly twice, a total of 20 matches need to be played.

The output shows one of the schedules that meet the conditions. No team plays on consecutive days.

Constraints:

• 2 <= n <= 50