Featured Puzzle: From 1 to X #1

From 1 to X doesn’t have a clear history as to who invented it, although it’s been around since at least 2006, when it was shown to be by Joachim Vetter in the publication Logisch. It’s not certain if that was the first appearance, though.

• Fill in the grid with numbers from 1 to X, where X is the size of the region.
• Digits may repeat within a row or column, unlike Sudoku.
• You may not place duplicate numbers in the same region, or in orthogonally adjacent cells across region borders.
• Numbers outside the grid indicate the sum of digits within that row or column.