Questions tagged [tic-tac-toe]

Puzzles centered around tic-tac-toe (a.k.a. noughts and crosses).

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Tic-Tac-Toe problem

In an infinite grid of regular triangles, Niels and Henrik are playing a game they made up. Every other time, Niels picks a triangle and writes × in it, and every other time, Henrik picks a triangle ...
13
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2answers
2k views

Tic-Tac-Toe Without a Predefined Board

On a warm and uneventful summer day, John and Mary passed the time by playing games of Tic-Tac-Toe, taking sticks and drawing in the soil. John and Mary are both child prodigies, so within two rounds ...
11
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1answer
634 views

A Tic-Tac-Toe variant with three marks - winning strategy and chances

We start with a usual $3 \times 3$ grid, $3$ different marks (say, $X, O, I$) and $2$ players. Player $A$ has to make a vertical, horizontal or diagonal line made of $3$ identical marks (XXX, OOO or ...
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0answers
127 views

Tic Tac Toe and random turn puzzle [closed]

I have a problem: There is a bag of 75 balls with 15 Red and rest Blue. I pick 4 balls at the start of every turn.If I get to pick at least 1 red ball, I fill 1 cell with X. If I get 3 red balls ...
7
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1answer
831 views

Tic Tac Toe Recursive

Related: Connect 4 Recursive We have a mega tic tac toe grid. Each of the nine cells of the mega grid has a smaller tic tac toe grid. In total we have 81 cells that can be filled. (Maybe imagine a ...
-4
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2answers
618 views

Optimal running-time tic-tac-toe algorithm

A perfect tic-tac-toe AI/algorithm would ideally never lose, but only win or draw, 100% of the time. Imagine that you play against once such algorithm, and it calculates the next move to make. Is ...
20
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2answers
1k views

Titanicker Tic-Tac-Toe

This is something of a follow-on to Hugh Meyer's enjoyable "Titanic Tic-Tac-Toe." Fortunately, our intrepid heroes Xavier and Oliver have wrested away a bit of wreckage that some fellow named Jack was ...
35
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1answer
1k views

Titanic Tic-Tac-Toe

Xavier and Oliver were playing tic-tac-toe on the Titanic using a wooden board and metal X's and O's. As the stern of the ship sank lower and lower they found, to their annoyance, that the pieces ...
2
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1answer
349 views

Another Tic-Tac-Toe problem

Two players A and B play Tic-Tac-Toe on an infinite 3-dimensional grid. Player A starts first and uses X, player B plays second and uses O. Every time player A places an X on the grid, player B can ...
16
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2answers
1k views

Tic-Tac-Toe variant

To help people think this out, I've made a web game with increasingly difficult cpu players to allow brainstorming and testing strategies: cpu player, easiest (version 1 - at least 5-in-a-row is ...
13
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2answers
934 views

Devising a sudoku where the rows are the moves for a draw in tic tac toe

The task is to construct a sudoku whose rows (or columns) are the moves for a game in tic tac toe where the game ends in a draw. Here are some clarifications and constraints which should limit ...
15
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3answers
1k views

N-dimensional Tic-Tac-Toe variant

Consider the game surface to be an infinite N dimensional Cartesian lattice. The rules are X moves first, but O gets to move ...
12
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3answers
2k views

Tic-tac-toe 1000 in a row

Consider a variant of Tic-Tac-Toe and Gomoku on a board that's infinite in every direction. X wins by getting a line of 1000 X's ...
5
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2answers
900 views

What is the smallest tic-tac-toe board to have a winning strategy?

There is not winning strategy for 9cell 3x3 board. There is a winning strategy for 16cell 4x4 board, or even for 10cell "3x3 + 1_cell_near_a_corner" board (see M.Gardner "Mathematical games"): $$ \...
36
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5answers
10k views

What is the optimal first move in tic-tac-toe?

I have been told that it is possible to guarantee no worse than a tie in normal 3x3 tic-tac-toe, but that the first move is very important. What is that important first move?