Multiple Construction

Enter an even-length sequence: the constructed array.

n: 1..10, each integer 1..n must appear exactly twice and no other numbers allowed.

- Example 1: 1, 2, 1, 2.
- Example 2: 1, 3, 1, 2, 3, 2.
- Example 3: 1, 1.

Hover a box to highlight its pair.