Elbow Room

Place one dot in every coloured region. No two dots may share a row or a column, and no two may touch, not even at a corner.

• -Place one dot in every coloured region of the 7 by 7 board.
• -One dot per region, per row and per column. Dots cannot touch, not even at a corner.
• -Tap a square once to cross it out, again to place a dot, and again to empty it. Drag across empty squares to cross out several at once. Crosses are notes for you and the rules ignore them.
• -Two dots that break a rule are marked red, with the row, column or region they share shaded, or both squares outlined if they touch. The puzzle is solved when every region has a dot and nothing is marked red.
• -You get two hints. Each one outlines the squares the next deduction is about and rings the square its dot goes in. Your result shows how many you used.
• -Every puzzle has exactly one solution, and you can reach it by reasoning without guessing. The rules are those of a classic pencil puzzle, Star Battle, with one star in each region.

Where to start

Start with the smallest region. A region of two or three squares has only that many places for its dot, so any square that every one of those places would rule out, by sharing its row or column or by touching it, can be crossed out before you look anywhere else. Then look for a region that sits entirely in one row or one column: its dot has to be in that line, so nothing from any other region can go there. The same works in reverse, when every open square in a row belongs to one region. When two regions fit inside the same two rows, those rows belong to them, and every other square in both rows is out. When you are stuck, picture a dot on a square and the squares it would rule out: if they leave a region with nowhere to go, that square is wrong.