Tic Tac Toe

Problem

N*N matrix is given with input red or black.You can move horizontally, vertically or diagonally. If 3 consecutive samecolor found, that color will get 1 point. So if 4 red are vertically then pointis 2. Find the winner.

Solution

注意检查左上到右下， 右上到左下

public static boolean ticTacToe(boolean[][] board) {
    if(board == null || board.length == 0)    return false;
    
    int m = board.length;
    int n = board[0].length;
    
    int red = 0, black = 0;
    for(int i=0; i<m; i++) {
        for(int j=0; j<n; j++) {
            if(board[i][j]) {
                if(i<m-2 && board[i+1][j] && board[i+2][j])    red++;    //check vertical
                if(j<n-2 && board[i][j+1] && board[i][j+2])    red++;    //check horizontal
                if(i<m-2 && j<n-2 && board[i+1][j+1] && board[i+2][j+2])    red++;    //check diag
            }
            else {
                if(i<m-2 && !board[i+1][j] && !board[i+2][j])    black++;    //check vertical
                if(j<n-2 && !board[i][j+1] && !board[i][j+2])    black++;    //check horizontal
                if(i<m-2 && j<n-2 && !board[i+1][j+1] && !board[i+2][j+2])    black++;    //check diag
            }
        }
    }
    
    for(int i=m-1; i>=0; i--) {
        for(int j=n-1; j>=0; j--) {
            if(board[i][j]) {
                if(i>=2 && j>=2 && board[i-1][j-1] && board[i-2][j-2])    red++;    //check reverse diag
            }
            else {
                if(i>=2 && j>=2 && !board[i-1][j-1] && !board[i-2][j-2])    black++;    //check reverse diag
            }
        }
    }
    
    return red > black;
}