159 Killer

Normal sudoku rules apply.

159: Digits in column 1 indicate the column in which the digit 1 appears in that row (e.g. if r4c1 is a 6, r4c6 is a 1). The same applies to columns 5 and 9, with the digits 5 and 9 respectively.

Killer: Digits in a cage sum to the small number given.