Riddle On a dark, moonless night, four friends are escaping a horde of 30 zombies. They come to an old rickety bridge. At most two can cross the bridge at a time and they must use a flashlight to see. They only have one flashlight, so someone must bring it back each time until everyone is across. Shaun takes 1 minute to cross, Liz takes 3, Ed takes 7 and Dianne takes 9. The zombies will get to the bridge in 20 minutes. How can everyone get across before the zombies arrive? Sudoku rules: Normal sudoku rules apply. Digits along an arrow sum to the digit in that arrow's circle. Digits on indicated diagonals sum to the pointing value. Rows 1,3,5,7,9 represent bridge crossings in order. The friends have to get from the left bank to the right. Place them on the bridge (ie the arrow) and the banks on either side. People are represented by their crossing time. The sandwich clues to the right indicate the total time after each crossing. A sandwich clue gives the sum of digits "sandwiched" between the 1 and 9 in their row.