348 Design Tic-Tac-Toe.py

"""
Design a Tic-tac-toe game that is played between two players on a n x n grid.

You may assume the following rules:

A move is guaranteed to be valid and is placed on an empty block.
Once a winning condition is reached, no more moves is allowed.
A player who succeeds in placing n of their marks in a horizontal, vertical, or
diagonal row wins the game.
Example:
Given n = 3, assume that player 1 is "X" and player 2 is "O" in the board.

TicTacToe toe = new TicTacToe(3);

toe.move(0, 0, 1); -> Returns 0 (no one wins)
|X| | |
| | | |    // Player 1 makes a move at (0, 0).
| | | |

toe.move(0, 2, 2); -> Returns 0 (no one wins)
|X| |O|
| | | |    // Player 2 makes a move at (0, 2).
| | | |

toe.move(2, 2, 1); -> Returns 0 (no one wins)
|X| |O|
| | | |    // Player 1 makes a move at (2, 2).
| | |X|

toe.move(1, 1, 2); -> Returns 0 (no one wins)
|X| |O|
| |O| |    // Player 2 makes a move at (1, 1).
| | |X|

toe.move(2, 0, 1); -> Returns 0 (no one wins)
|X| |O|
| |O| |    // Player 1 makes a move at (2, 0).
|X| |X|

toe.move(1, 0, 2); -> Returns 0 (no one wins)
|X| |O|
|O|O| |    // Player 2 makes a move at (1, 0).
|X| |X|

toe.move(2, 1, 1); -> Returns 1 (player 1 wins)
|X| |O|
|O|O| |    // Player 1 makes a move at (2, 1).
|X|X|X|
Follow up:
Could you do better than O(n2) per move() operation?
Author: Rajeev Ranjan

"""

class TicTacToe(object):
    def __init__(self, n):
        """
        Initialize your data structure here.
        :type n: int
        """
        self.n = n
        self.rows_count = [0 for _ in xrange(n)]
        self.cols_count = [0 for _ in xrange(n)]
        self.diag_count = 0
        self.diag_inv_count = 0

    def move(self, row, col, player):
        """
        Since guarantee the move is valid, only store row, col, diagonal.
        1: -1
        2: +1
        Player {player} makes a move at ({row}, {col}).
        @param row The row of the board.
        @param col The column of the board.
        @param player The player, can be either 1 or 2.
        @return The current winning condition, can be either:
                0: No one wins.
                1: Player 1 wins.
                2: Player 2 wins.
        :type row: int
        :type col: int
        :type player: int
        :rtype: int
        """
        delta = -1 if player == 1 else 1
        self.cols_count[col] += delta
        self.rows_count[row] += delta
        if col == row:
            self.diag_count += delta
        if col + row == self.n - 1:
            self.diag_inv_count += delta

        # since winning condition is taking up the entire row or col, the row or col must be consecutive
        is_win = lambda count: delta * count == self.n
        if any(map(is_win, [self.rows_count[row], self.cols_count[col], self.diag_count, self.diag_inv_count])):
            return player

        return 0

# Your TicTacToe object will be instantiated and called as such:
# obj = TicTacToe(n)
# param_1 = obj.move(row,col,player)