Problem
A 3×3 board is given as three strings of X, O and . (empty). A player wins with three of their marks in a row, column or diagonal. Boards never have two winners.
Implement tic_tac_toe_winner(board).
Input
board: Three rows of three characters each.
Output
Return "X" or "O" for the winner, "Draw" if the board is full with no winner, or "Pending" if empty cells remain and nobody has won.
Constraints
board has exactly 3 rows of length 3
Examples
Input:
board = ["XOX", ".X.", "O.X"]
Expected output:
expected = "X"Input:
std::vector<std::string> board = {"XOX", ".X.", "O.X"};
Expected output:
std::string expected = "X";Input:
string[] board = new string[] {"XOX", ".X.", "O.X"};
Expected output:
string expected = "X";Explanation
X holds the diagonal from top-left to bottom-right, so X wins.
Input:
board = ["XOX", "XOO", "OXX"]
Expected output:
expected = "Draw"Input:
std::vector<std::string> board = {"XOX", "XOO", "OXX"};
Expected output:
std::string expected = "Draw";Input:
string[] board = new string[] {"XOX", "XOO", "OXX"};
Expected output:
string expected = "Draw";Explanation
The board is full and no line has three of a kind: Draw.
How to approach it
Try on your own first, then open one hint at a time.
Hint 1
Check every row, column, and the two diagonals for three identical non-empty marks.
Hint 2
Track whether any empty cells remain while scanning the board once.
Hint 3
Remember that a full board with no winner is a draw, otherwise it is pending.
Expected complexity
O(1) time, O(1) extra space
References
This challenge is adapted for CodeUtility. Follow the statement and constraints above.