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.
Solution:
using System;
using System.Collections.Generic;
using System.Text;
namespace LeetCode.AskGif.Easy.Array
{
public class TictactoeSoln
{
public string Tictactoe(int[][] moves)
{
var matrix = new char[3, 3];
var playerA = true;
var input = 'X';
for (int i = 0; i < moves.Length; i++)
{
if (!playerA)
{
input = 'O';
}
else
{
input = 'X';
}
playerA = !playerA;
//considering inputs are valid
matrix[moves[i][0], moves[i][1]] = input;
var check = ValidateMatrix(matrix);
switch (check)
{
case "O":
return "B";
case "X":
return "A";
case "Draw":
return "Draw";
case "Pending":
break;
}
}
return "Pending";
}
private string ValidateMatrix(char[,] matrix)
{
char defaultValue = '\0';
//First row
if(matrix[0, 0] != defaultValue && matrix[0, 0] == matrix[0, 1] && matrix[0, 0] == matrix[0, 2])
{
return matrix[0, 0].ToString();
}
//Second row
if (matrix[1, 0] != defaultValue && matrix[1, 0] == matrix[1, 1] && matrix[1, 0] == matrix[1, 2])
{
return matrix[1, 0].ToString();
}
//Third row
if (matrix[2, 0] != defaultValue && matrix[2, 0] == matrix[2, 1] && matrix[2, 0] == matrix[2, 2])
{
return matrix[2, 0].ToString();
}
//First Column
if (matrix[0, 0] != defaultValue && matrix[0, 0] == matrix[1, 0] && matrix[0, 0] == matrix[2, 0])
{
return matrix[0, 0].ToString();
}
//Second Column
if (matrix[0, 1] != defaultValue && matrix[0, 1] == matrix[1, 1] && matrix[0, 1] == matrix[2, 1])
{
return matrix[0, 1].ToString();
}
//Third Column
if (matrix[0, 2] != defaultValue && matrix[0, 2] == matrix[1, 2] && matrix[0, 2] == matrix[2, 2])
{
return matrix[0, 2].ToString();
}
//Diagonal
if (matrix[0, 0] != defaultValue && matrix[0, 0] == matrix[1, 1] && matrix[0, 0] == matrix[2, 2])
{
return matrix[0, 0].ToString();
}
//Diagonal
if (matrix[0, 2] != defaultValue && matrix[0, 2] == matrix[1, 1] && matrix[0, 2] == matrix[2, 0])
{
return matrix[0, 2].ToString();
}
//Check if any block is available to play
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 3; j++)
{
if(matrix[i,j] == defaultValue)
{
return "Pending";
}
}
}
return "Draw";
}
}
}
Time Complexity: O(n)
Space Complexity: O(n) To Create Matrix
Unit Tests:
using LeetCode.AskGif.Easy.Array;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;
using System.Text;
namespace CodingUnitTest.Easy.Array
{
[TestClass]
public class TictactoeSolnTests
{
[TestMethod]
public void TictactoeSoln_First()
{
var moves = new int[,] {
{ 0, 0 },
{ 2, 0 },
{ 1, 1 },
{ 2, 1 },
{ 2, 2 }
};
var output = "A";
var res = new TictactoeSoln().Tictactoe(ArrayMapper(moves));
Assert.AreEqual(res, output);
}
[TestMethod]
public void TictactoeSoln_Second()
{
var moves = new int[,] {
{ 0, 0 },
{ 1, 1 },
{ 0, 1 },
{ 0, 2 },
{ 1, 0 },
{ 2, 0 }
};
var output = "B";
var res = new TictactoeSoln().Tictactoe(ArrayMapper(moves));
Assert.AreEqual(res, output);
}
[TestMethod]
public void TictactoeSoln_Third()
{
var moves = new int[,] {
{ 0, 0 },
{ 1, 1 },
{ 2, 0 },
{ 1, 0 },
{ 1, 2 },
{ 2, 1 },
{ 0, 1 },
{ 0, 2 },
{ 2, 2 }
};
var output = "Draw";
var res = new TictactoeSoln().Tictactoe(ArrayMapper(moves));
Assert.AreEqual(res, output);
}
[TestMethod]
public void TictactoeSoln_Fourth()
{
var moves = new int[,] {
{ 0, 0 },
{ 1, 1 }
};
var output = "Pending";
var res = new TictactoeSoln().Tictactoe(ArrayMapper(moves));
Assert.AreEqual(res, output);
}
private int[][] ArrayMapper(int[,] matrix)
{
var arr = new int[matrix.GetLength(0)][];
for (int i = 0; i < matrix.GetLength(0); i++)
{
arr[i] = new int[matrix.GetLength(1)];
for (int j = 0; j < matrix.GetLength(1); j++)
{
arr[i][j] = matrix[i, j];
}
}
return arr;
}
}
}
