https://leetcode.com/problems/valid-tic-tac-toe-state

valid-tic-tac-toe-state.java

class Solution {
    public boolean validTicTacToe(String[] board) {
        int[] row = new int[3];
        int[] col = new int[3];
        int diag = 0;
        int anti = 0;
        int xMove = 0;
        int oMove = 0;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                if (board[i].charAt(j) == 'X') {
                    row[i] += 1;
                    col[j] += 1;
                    if (i == j) diag += 1;
                    if (j + i == 2) anti += 1;
                    xMove += 1;
                } else if (board[i].charAt(j) == 'O') {
                    row[i] -= 1;
                    col[j] -= 1;
                    if (i == j) diag -= 1;
                    if (i + j == 2) anti -= 1;
                    oMove += 1;
                }
            }
        }
        if (xMove - oMove > 1 || xMove - oMove < 0) {
            return false;
        }
        
        boolean xWin = false;
        for (int i = 0; i < 3; i++) {
            xWin |= (row[i] == 3);
            xWin |= (col[i] == 3);
        }
        xWin |= (diag == 3);
        xWin |= (anti == 3);
        
        boolean oWin = false;
        for (int i = 0; i < 3; i++) {
            oWin |= (row[i] == -3);
            oWin |= (col[i] == -3);
        }
        oWin |= (diag == -3);
        oWin |= (anti == -3);
        if (xWin && oWin || (xMove - oMove == 0 && xWin) || (xMove - oMove == 1 && oWin)) {
            return false;
        }
        return true;
    }
}