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ValidTicTacToeState.java
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88 lines (85 loc) · 3.08 KB
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package array;
/**
* Created by gouthamvidyapradhan on 29/03/2019
* A Tic-Tac-Toe board is given as a string array board. Return True if and only if it is possible to reach this
* board position during the course of a valid tic-tac-toe game.
*
* The board is a 3 x 3 array, and consists of characters " ", "X", and "O". The " " character represents an empty
* square.
*
* Here are the rules of Tic-Tac-Toe:
*
* Players take turns placing characters into empty squares (" ").
* The first player always places "X" characters, while the second player always places "O" characters.
* "X" and "O" characters are always placed into empty squares, never filled ones.
* The game ends when there are 3 of the same (non-empty) character filling any row, column, or diagonal.
* The game also ends if all squares are non-empty.
* No more moves can be played if the game is over.
* Example 1:
* Input: board = ["O ", " ", " "]
* Output: false
* Explanation: The first player always plays "X".
*
* Example 2:
* Input: board = ["XOX", " X ", " "]
* Output: false
* Explanation: Players take turns making moves.
*
* Example 3:
* Input: board = ["XXX", " ", "OOO"]
* Output: false
*
* Example 4:
* Input: board = ["XOX", "O O", "XOX"]
* Output: true
* Note:
*
* board is a length-3 array of strings, where each string board[i] has length 3.
* Each board[i][j] is a character in the set {" ", "X", "O"}.
*
* Solution: Do a brute-force check for each row, column and diagonals and keep track of count of 'X' and 'O'
*/
public class ValidTicTacToeState {
/**
* Main method
* @param args
*/
public static void main(String[] args) {
String[] board = {"XXX", "XOO", "OO "};
System.out.println(new ValidTicTacToeState().validTicTacToe(board));
}
public boolean validTicTacToe(String[] board) {
boolean xWon = hasWon(board, 'X');
boolean oWon = hasWon(board, 'O');
int xcount = 0, ocount = 0;
for(int i = 0; i < 3; i ++){
for(int j = 0; j < 3; j ++){
if(board[i].charAt(j) == 'X'){
xcount++;
}else if(board[i].charAt(j) == 'O'){
ocount++;
}
}
}
if(xWon && oWon) return false;
if(xWon){
return ((xcount - 1 == ocount));
} else if(oWon){
return ((xcount == ocount));
} else {
return (xcount == ocount || xcount - 1 == ocount);
}
}
private boolean hasWon(String[] board, char c){
boolean diagnol = ((board[0].charAt(0) == c && board[1].charAt(1) == c && board[2].charAt(2) == c) ||
(board[0].charAt(2) == c && board[1].charAt(1) == c && board[2].charAt(0) == c));
if(diagnol) return true;
for(int i = 0; i < 3; i ++){
if(board[i].charAt(0) == c && board[i].charAt(1) == c && board[i].charAt(2) == c) return true;
}
for(int i = 0; i < 3; i ++){
if(board[0].charAt(i) == c && board[1].charAt(i) == c && board[2].charAt(i) == c) return true;
}
return false;
}
}