1275. Find Winner on a Tic Tac Toe Game ---E

Tic-tac-toe is played by two players A and B on a 3 x 3 grid.

Here are the rules of Tic-Tac-Toe:

• Players take turns placing characters into empty squares (" ").
• The first player A always places "X" characters, while the second player B always places "O" characters.
• "X" and "O" characters are always placed into empty squares, never on 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.

Given an array moves where each element is another array of size 2 corresponding to the row and column of the grid where they mark their respective character in the order in which A and B play.

Return the winner of the game if it exists (A or B), in case the game ends in a draw return "Draw", if there are still movements to play return "Pending".

You can assume that moves is valid (It follows the rules of Tic-Tac-Toe), the grid is initially empty and A will play first.

 

Example 1:

Input: moves = [[0,0],[2,0],[1,1],[2,1],[2,2]]
Output: "A"
Explanation: "A" wins, he always plays first.
"X  "    "X  "    "X  "    "X  "    "X  "
"   " -> "   " -> " X " -> " X " -> " X "
"   "    "O  "    "O  "    "OO "    "OOX"

Example 2:

Input: moves = [[0,0],[1,1],[0,1],[0,2],[1,0],[2,0]]
Output: "B"
Explanation: "B" wins.
"X  "    "X  "    "XX "    "XXO"    "XXO"    "XXO"
"   " -> " O " -> " O " -> " O " -> "XO " -> "XO " 
"   "    "   "    "   "    "   "    "   "    "O  "

Example 3:

Input: moves = [[0,0],[1,1],[2,0],[1,0],[1,2],[2,1],[0,1],[0,2],[2,2]]
Output: "Draw"
Explanation: The game ends in a draw since there are no moves to make.
"XXO"
"OOX"
"XOX"

Example 4:

Input: moves = [[0,0],[1,1]]
Output: "Pending"
Explanation: The game has not finished yet.
"X  "
" O "
"   "

 

Constraints:

• 1 <= moves.length <= 9
• moves[i].length == 2
• 0 <= moves[i][j] <= 2
• There are no repeated elements on moves.
• moves follow the rules of tic tac toe.

A:

class Solution {
public:
    string tictactoe(vector<vector<int>>& moves) {
        vector<vector<char>> T(3, vector<char>(3));
        for(int i =0;i<moves.size();i++){
            auto move = moves[i];
            int x = move[0], y = move[1];
            if(i%2==0)
                T[x][y] = 'X';
            else
                T[x][y] = 'O';
            if(isWin(T, x, y)){                
                return (i%2==0) ? "A" : "B";
            }
        }
        return moves.size()<9? "Pending" : "Draw";
    }
private:
    bool isWin(vector<vector<char>> &T, int x ,int y){
        char ch = T[x][y];
        // check row
        int c = 0;
        for(int i=0;i<3;i++)
            if(T[i][y] == ch)
                c++;
        if(c==3)
            return true;
        
        // check col
        c = 0;
        for(int j=0;j<3;j++)
            if(T[x][j] == ch)
                c++;
        if(c==3)
            return true;
        // check \ diagnal
        if(x==y){
            c = 0;
            for(int i =0;i<3;i++)
                if(T[i][i] == ch)
                    c++;
            if(c==3)
                return true;
        }
        // check / diagnal
        if(x+y==2){
            c = 0;
            for(int i =0;i<3;i++)
                if(T[i][2-i] == ch)
                    c++;
            if(c==3)
                return true;
        }
        return false;
    }
};