Logic Masters Deutschland e.V.

Loop Knight Region

Rules:

Normal sudoku rules apply. Digits separated by knight's move can't be the same. Draw a single closed loop that moves cell to cell orthogonally and passes through on exactly 8 of the boxes (which box it doesn't pass must be determined by the solver and we call this box 'bad'). The loop may not touch itself orthogonally. Each cell on the 'bad' box and each corner cell of the grid (means r1c1, r1c9, r9c1 and r9c9 which can be part of the loop) doesn't see any cell which is part of the loop by knight's move. Each cell on the grid doesn't see more than 4 cells which are part of the loop by knight's move. Furthermore, this loop acts as a region sum line, the sum of the digits along the loop must be the same within each 3x3 box the loop passes through each time.

CTC