Killer Sudoku Zero

Killer Sudoku Zero is Killer Variant #8. Some inner shapes have been removed! The rules are as follows: Place the digits from 1-9 into each row, column and 3x3 box once. The numbers in each inner shape must add up to the number at the top-left corner of that inner shape. No number can be repeated in an inner shape. Some inner shapes have been removed, making the puzzle harder.