# the 0 and cross problem

Note by Harsh Mohan
5 years, 3 months ago

MarkdownAppears as
*italics* or _italics_ italics
**bold** or __bold__ bold
- bulleted- list
• bulleted
• list
1. numbered2. list
1. numbered
2. list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1paragraph 2

paragraph 1

paragraph 2

[example link](https://brilliant.org)example link
> This is a quote
This is a quote
    # I indented these lines
# 4 spaces, and now they show
# up as a code block.

print "hello world"
# I indented these lines
# 4 spaces, and now they show
# up as a code block.

print "hello world"
MathAppears as
Remember to wrap math in $$...$$ or $...$ to ensure proper formatting.
2 \times 3 $$2 \times 3$$
2^{34} $$2^{34}$$
a_{i-1} $$a_{i-1}$$
\frac{2}{3} $$\frac{2}{3}$$
\sqrt{2} $$\sqrt{2}$$
\sum_{i=1}^3 $$\sum_{i=1}^3$$
\sin \theta $$\sin \theta$$
\boxed{123} $$\boxed{123}$$

Sort by:

X went first. I'm making the assumption that 1. Both will complete your 3-in-a-line if they can (and hence win) 2. Both will play to prevent the other from getting a 3-in-the-line (and hence not lose immediately) 3. Other than that, you are allowed to play in any way.

If O went first, then by his second turn he must have obtained 2 in a row (since any 2 of the 3 O's are in a line). This means that X will need to block it (since X cannot win in the 2nd turn), thus the first 2 O's placed must be in the middle column (the order doesn't matter), and the 2nd X placed must be the top middle one. Hence, the third O placed must be in the bottom left corner, after which X will need to play in either the top right or bottom right to prevent the 3-in-a-line.

Hence, we are left with the case that X went first. We also need to verify that a sequence of moves is possible. See Aditya's comment.

Staff - 5 years, 3 months ago

It is "x's" turn. I tried most of the moves that would lead to this and I could narrow down to one solution, where X first plays In the 1st row 2nd column, then zero is made in the centre. Next, x is made in the 2nd row 1st column and zer0 in the 3rd row 2nd column. Finally, x is played in the 1st box and the zero in the 3rd row 1st column. This might not be the perfect solution though.

- 5 years, 3 months ago

If this is a classical tic-tac-toe,I think the moves that you have suggested in your solution is a bit illogical .They are not looking for a chance to get themselves in a row of 3 same symboles.

- 5 years, 3 months ago

Then any two players playing rationally would never arrive at this situation. Though it is important to note that sometimes negligence can lead to this pattern. Methinks.

- 5 years, 3 months ago

Ok,got it.

- 5 years, 3 months ago

X

- 5 years, 3 months ago

it seems 0 has made a riddle 2 win the game becuz next is of X but unfortunately X may win hence next turn is of X

- 5 years, 2 months ago

next turn is of X bcuz he is not a fool to loose such an easy game

- 5 years, 2 months ago

arent we assuming that the players dont do a one move blunder??

- 5 years, 3 months ago

whoever went first - it's his turn now we have to decide who went first if we assume that x was not dumb 0 cannot possibly go first - i tried every possible move with 0 starting first and every time got to a situation where the THIRD move of x must be to block 0's next move which is obviously not the case here so we can safely assume that x went first and it's his turn

- 5 years, 3 months ago

its x's turn

- 5 years, 3 months ago

0 in that game fist user can be enered in a squre box first so enter 0 in next

- 5 years, 3 months ago

its X turn as it the player of X will not let the O player to get both ways to win without closing one path (diagonal or horizontal). Logically its X's turn

- 5 years, 3 months ago

Well talking about logic...X gave a chance to O for wining.. :)

- 5 years, 3 months ago

Well see,game starts with X,then O and again X and so on... At any instant of the game Number of O CAN NEVER BE MORE THAN X,here number of X and O is same so it has to be X's turn

- 5 years, 3 months ago

Dude, 'x' need not be first.

- 5 years, 3 months ago

yes..the game stars with X..

- 5 years, 3 months ago

of 0 one

- 5 years, 3 months ago

calvin sir can you help us with this?

- 5 years, 3 months ago

think about it like this x has one position from where he can win but but 0 has two winning positions.........so if 0 had to win he would have until now......but its not.....so naturally it is 0's turn....aye?

- 5 years, 3 months ago

X's turn. I tried to simulate it as if O had started but if that was the case O's moves would not be logical.

- 5 years, 3 months ago

the person who played first

- 5 years, 3 months ago

you have to either answer zero or cross. state your reason as well.

- 5 years, 3 months ago

i hv read a similar prob in a puzzle book...

- 5 years, 3 months ago

its turn of player using 0 symbol

- 5 years, 3 months ago

Case chase ! , I will scan and give you my solution today !

- 5 years, 3 months ago

actually in both the players playing have made the blunder because 1 of the two players actually had a chance to win the game but refuse to do so. So, both x and o can the next turn

- 5 years, 3 months ago

They refused to do so in the previous steps

- 5 years, 3 months ago

I agree. Got the same answer.

- 5 years, 3 months ago

I guess 0 because starting with the middle is usually the best first move in tic-tac-toe. Just based on common strategies used in this game.

- 5 years, 3 months ago

cross, my moves... 1st cross of second row, then zero of third row & second column, then cross of 1st row & 2nd column, then zero of middle one, then cross then zero ...so, next chance cross....too lazy to type reason

- 5 years, 3 months ago

It has to be 'x' simply because any two of the three circles force the 'x' player to respond to it, assuming both players are playing 'reasonably' and not just filling up squares randomly - thus after the circle player's second move, 'x' must respond; after the circle player's third move, the X player must respond again; looking at the board, X has only responded once by blocking a line of three; its thus his turn again

(Was wrong initially; edited)

- 5 years, 3 months ago

What if it is the opposite way round??

- 5 years, 3 months ago

x as usually x starts and they have 3 turns each

- 5 years, 3 months ago