Explanation
Open the explanation (shows the answer)
The answer is a7. With best play to the end: ±0 (a draw).
Best line: a7 b8 b4 d2 c3 c2 d1 c1 a1 e1
Other moves
| Move | Result | Why |
|---|---|---|
| b4 | -4 (a loss by 4) | The opponent's best answer is a7 (then b8 d2 g1). |
| c3 | -8 (a loss by 8) | Opponent's moves: 6 after this move, 4 after a7. The opponent's best answer is b2 (then a7 b8 a1). |
| d1 | -8 (a loss by 8) | Opponent's moves: 7 after this move, 4 after a7. The opponent's best answer is a7 (then b8 e1 b4). |
| g1 | -12 (a loss by 12) | Opponent's moves: 6 after this move, 4 after a7. The opponent's best answer is e1 (then a7 b8 b4). |
| e1 | -14 (a loss by 14) | Opponent's moves: 6 after this move, 4 after a7. Openness: 3 for this move (flips 2), 1 for a7 (flips 1). The opponent's best answer is b8 (then b4 c3 a7). |
| b8 | -28 (a loss by 28) | The opponent's best answer is d2 (then g1 e1 b4). |
About these puzzles
Each position comes from a real game. The engine solved it to the end (perfect play by both sides) and only positions with a single best move, clearly better than the second-best move, were kept. "Best play wins by N" is the final disc margin when both sides play perfectly.
If you play a different move, you see the final margin your move leads to with perfect play afterwards, and how much it gave up. Results are stored only in this browser.
To be graded during a full game, go to the Reversi dojo.