Formatted question description: https://leetcode.ca/all/1275.html

# 1275. Find Winner on a Tic Tac Toe Game (Easy)

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.

**Related Topics**:

Array

## Solution 1.

```
// OJ: https://leetcode.com/problems/find-winner-on-a-tic-tac-toe-game/
// Time: O(1)
// Space: O(1)
class Solution {
string check(int A[3][3]) {
for (int i = 0; i < 3; ++i) {
int j = 1;
while (j < 3 && A[i][0] != 0 && A[i][j] == A[i][0]) ++j;
if (j == 3) return A[i][0] == 1 ? "A" : "B";
j = 1;
while (j < 3 && A[0][i] != 0 && A[j][i] == A[0][i]) ++j;
if (j == 3) return A[0][i] == 1 ? "A" : "B";
}
int i = 1;
while (i < 3 && A[0][0] != 0 && A[i][i] == A[0][0]) ++i;
if (i == 3) return A[0][0] == 1 ? "A" : "B";
i = 1;
while (i < 3 && A[0][2] != 0 && A[i][2 - i] == A[0][2]) ++i;
if (i == 3) return A[0][2] == 1 ? "A" : "B";
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < 3; ++j) {
if (A[i][j] == 0) return "Pending";
}
}
return "Draw";
}
public:
string tictactoe(vector<vector<int>>& moves) {
int A[3][3] = {}, ch = 1;
for (auto &m : moves) {
A[m[0]][m[1]] = ch;
ch = ch == 1 ? 2 : 1;
}
return check(A);
}
};
```

## Solution 2.

```
// OJ: https://leetcode.com/problems/find-winner-on-a-tic-tac-toe-game/
// Time: O(1)
// Space: O(1)
class Solution {
public:
string tictactoe(vector<vector<int>>& moves) {
int A[8] = {}, B[8] = {};
for (int i = 0; i < moves.size(); ++i) {
int r = moves[i][0], c = moves[i][1];
if (i % 2 == 0 && (++A[r] == 3 || ++A[3 + c] == 3 || (r == c && ++A[6] == 3) || (r == 2 - c && ++A[7] == 3))) return "A";
if (i % 2 && (++B[r] == 3 || ++B[3 + c] == 3 || (r == c && ++B[6] == 3) || (r == 2 - c && ++B[7] == 3))) return "B";
}
return moves.size() == 9 ? "Draw" : "Pending";
}
};
```

Java

```
class Solution {
public String tictactoe(int[][] moves) {
final char[] SIGNALS = {'X', 'O'};
final int SIDE = 3;
char[][] board = new char[SIDE][SIDE];
int[][] countRows = new int[2][SIDE];
int[][] countColumns = new int[2][SIDE];
int[][] countDiagonals = new int[2][2];
int length = moves.length;
for (int i = 0; i < length; i++) {
int player = i % 2;
int[] move = moves[i];
int row = move[0], column = move[1];
board[row][column] = SIGNALS[player];
int countRow = countRows[player][row];
countRow++;
countRows[player][row] = countRow;
if (countRow == SIDE)
return player == 0 ? "A" : "B";
int countColumn = countColumns[player][column];
countColumn++;
countColumns[player][column] = countColumn;
if (countColumn == SIDE)
return player == 0 ? "A" : "B";
if (row == column) {
int countDiagonal = countDiagonals[player][0];
countDiagonal++;
countDiagonals[player][0] = countDiagonal;
if (countDiagonal == SIDE)
return player == 0 ? "A" : "B";
}
if (row + column == SIDE - 1) {
int countDiagonal = countDiagonals[player][1];
countDiagonal++;
countDiagonals[player][1] = countDiagonal;
if (countDiagonal == SIDE)
return player == 0 ? "A" : "B";
}
}
if (length == 9)
return "Draw";
else
return "Pending";
}
}
```