Logic Masters Deutschland e.V.

This is the eighth puzzle in my '3 Series'.

I made this puzzle months ago, but did not have the energy to publish it. Please enjoy.

Solve on SudokuPad

Rules:

Normal sudoku rules apply: Place the digits 1 to 6 once each, in every row, column and box.

Japanese Sums: Shade some cells, such that the clues outside the grid indicate the sums of the digits in contiguous block of unshaded cells in the respective row or column. A question mark represents any number. Blocks have to be separated by at least one shaded cell.

Skyscrapers: Some clues outside the grid indicate how many digits in the grid can be "seen" when looking into the grid along the row or column. A digit is visible only when it is larger than all digits in the grid that appear before it along the line of sight.

All clues outside the grid are Japanese Sums clues. Every clue, that is a valid Skyscraper clue, is marked with a rectangle.