Two Colour Theorem
by Blobz, FullDeck, Missing a Few Cards and Ms Blobz Open on SudokuPad
Heartburn
- Shading
- Region sum lines
The brief
Normal sudoku rules apply. Shade cells using two colours such that each colour forms an orthogonally connected region, and no 2x2 area is a single colour. Digits in caged cells indicate how many cells of the same colour are seen orthogonally from that position, including itself. The other colour blocks vision. Box borders divide blue lines into segments with the same sum. Along lines, colours must change at box boundaries and may not change within the box. The intersecting lines at R34C89 each continue straight and do not branch.