5275. Find Winner on a Tic Tac Toe Game

 

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.

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/find-winner-on-a-tic-tac-toe-game
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把下棋步骤输进去，直接判断3*3棋盘有没有赢，赢了就return

没有赢看是不是下了九次，判断平局还是可以继续。

class Solution {
public:
    string tictactoe(vector<vector<int>>& moves) {
        vector<vector<int>>vv;
        for(int i=0;i<3;i++){
            vector<int>v(3);
            vv.push_back(v);
        }
        int flag=0;
        for(int i=0;i<moves.size();i++){
            int a=moves[i][0];
            int b=moves[i][1];
            if(i%2==0){
                flag=1;
            }else{
                flag=-1;
            }
            vv[a][b]=flag;
            if((vv[a][0]==flag&&vv[a][1]==flag&&vv[a][2]==flag)||(vv[0][b]==flag&&vv[1][b]==flag&&vv[2][b]==flag)||(vv[0][0]==flag&&vv[1][1]==flag&&vv[2][2]==flag)||(vv[0][2]==flag&&vv[1][1]==flag&&vv[2][0]==flag)){
                if(flag==1){
                    return "A";
                }else{
                    return "B";
                }
            }
            
        }
        if(moves.size()<9){
            return "Pending";
        }else{
            return "Draw";
        }
    }
};