Cách đến Win Tic-Tac-Toe (và Never Lose): Miễn phí Chiến lượ

To win tic-tac-toe, go first và start in a corner, then try đến create a fork: a move that makes two lines of two at once, so của bạn opponent có thể block only one. To never lose, learn right reply đến each opening: answer a corner với centre, centre với a corner, và always block a fork before it happens. With perfect play từ both sides trò chơi là always a draw. Test yourself against unbeatable computer in free Tic-Tac-Toe game.

We checked every line below by computer, searching all 255,168 possible games.

The three kinds of square

The board has nine squares, và they're not equal:

• Centre: on four lines (a row, a column và both diagonals).
• Corners: on three lines each.
• Edges ( middle of each side): on only two lines each.

More lines means more chances đến make threats, which là why centre và corners là stronger than edges.

Rule 1: Win nếu bạn có thể, block nếu bạn must

Every turn, check in this order:

1. Can bạn complete a line? Do it.
2. Can của bạn opponent complete a line next turn? Block it.
3. Can bạn make a fork? Do it.
4. Can của bạn opponent make a fork next turn? Stop it, ideally by making a two-in-a-row that forces them đến block bạn instead.

Most casual games là lost at step 2: someone misses a block. Most "good người chơi" games là decided at steps 3 và 4.

Cách đến win tic-tac-toe với a fork

Here's a real example. You're X và start in top-left corner. O takes centre. You take bottom-right corner. O now makes a mistake và takes top-right corner, threatening diagonal từ top-right đến bottom-left.

You must block in bottom-left corner, but look what that block does: bạn now threaten left-hand column và bottom row at same time. O có thể stop only one, và bạn complete other. That double threat là a fork, và it's only way đến beat a người chơi who never misses a simple block.

Going first: corner opening

Opening in a corner là most testing start. Of eight replies, only centre avoids a loss cho O. Nếu của bạn opponent plays anything else, there's a forced win:

• O takes opposite corner: take one of two remaining corners. You threaten a line và sẽ set up a fork.
• O takes an edge hoặc an adjacent corner: bạn có thể also force a win, usually by taking another corner that creates a threat và then a fork.

Nếu O correctly takes centre, trò chơi should be a draw, but there's still a trap. Take opposite corner. Now O must reply on an edge; nếu O takes a corner instead, bạn có thể fork và win.

Going first: centre opening

Starting in centre là solid. Here O must reply in a corner: any edge reply loses. After centre, then a corner từ O, try corner opposite O's. Now O has đến take another corner; an edge loses.

Edge openings là weakest start cho X, though still not a losing one.

Going second: how đến never lose

You'll often move second. In our trò chơi, X và O take turns starting each new trò chơi, so against computer bạn play second every other trò chơi. The safe replies:

Opponent opens	Your safe reply	Replies that lose
Corner	The centre	Any other square
Centre	Any corner	Any edge
Edge	The centre, either corner next đến it, hoặc opposite edge	The other four squares

Then keep applying Rule 1. Two further traps đến remember khi playing second:

• You have centre và X has two opposite corners: play an edge, not a corner.
• X has centre và corner opposite yours: take another corner, not an edge.

Playing computer

Chọn Against computer và a level:

Level	Cách it plays	Can bạn win?
Easy	Often places marks at random	Yes, often. Practise setting up forks.
Medium	Usually plays best move, sometimes slips	Yes, khi it slips. Punish mistakes.
Unbeatable	Always plays a perfect move	No. A draw là best result.

On Unbeatable, của bạn goal là never đến lose. Nếu bạn có thể draw ten games in a row, including ones where computer moves first, bạn've learned trò chơi. The score cho each side và draws là kept in của bạn browser; Reset score clears them.

Chọn Two người chơi đến play a friend on same device, which là great cho teaching children fork idea.

Vì sao perfect tic-tac-toe là a draw

Because board là so small, every position có thể be worked out completely. When both sides follow rules above, no one ever gets a fork that có thể't be stopped, so trò chơi always fills up với no line. That's why tic-tac-toe là a good first strategy trò chơi: bạn có thể master it in an afternoon.

For a bigger challenge built on same "make two threats at once" idea, try Four in a Row. Our guide on how to win Connect 4 shows how forks work on a bigger board.

Practise now

Pick Unbeatable và see nếu bạn có thể hold it đến a draw từ both sides. The free Tic-Tac-Toe game runs in của bạn browser với no download hoặc sign-up.