Tic Tac Toe Challenge 233

Logic Level 2

X and O are playing tic-tac-toe, and it's now O's turn.

Assuming both are playing optimally, where must O put the mark to draw the match?

Enter your answer as the sum of the numbers in all possible spaces. For example, if you think it's the spaces with 5 or 6, then enter 5 + 6 = 11.

The answer is 7.

2 solutions

X X
May 6, 2018

Stop the x from getting to 1,because the L shape means losing.Putting on 2 and 4 will also block the opponent from forming the L shape.We get 1+2+4=7

Why 7?! If the answer is 7 then they are not playing optimally, if I put on 1 then X (if plays optimally) tries to stop me and go on 6, the I go to 4, he again tries to stop me and go to 2, then I stop him and go to 3, it's a draw. 1+4+3=8 Or O-1, X-6, O-2, X-4, O-5 it's a draw 1+2+5=8

No Body - 3 years, 1 month ago

The question is asking the first move of X,you can put at 1,2,4

X X - 3 years, 1 month ago

Keertana Pillai
May 24, 2018

The one way X can win for sure is if X creates a double-trap. O's aim should be to prevent X from creating the aforementioned double-trap. If X wants to create such a trap, X would place a piece in square 1 because it is where the first row and first column intersect. Hence, O may place a piece in either square 1 , square 2 or square 4 as doing so invalidates the use of either the first column or first row or both in the creation of a double trap. Thus, the answer, expressed as a sum of the number representing the squares in which O may successfully place a piece to defend itself is 1+2+4=7

Tic Tac Toe Challenge 233

The answer is 7.

2 solutions

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