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Challenge 153: Tic-Tac-Toe

curriculum/challenges/english/blocks/daily-coding-challenges-javascript/69373793f5a867f769cde138.md

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--description--

Given a 3×3 matrix (an array of arrays) representing a completed Tic-Tac-Toe game, determine the winner.

  • Each element in the given matrix is either an "X" or "O".

A player wins if they have three of their characters in a row - horizontally, vertically, or diagonally.

Return:

  • "X wins" if player X has three in a row.
  • "O wins" if player O has three in a row.
  • "Draw" if no player has three in a row.

--hints--

ticTacToe([["X", "X", "X"], ["O", "O", "X"], ["O", "X", "O"]]) should return "X wins".

js
assert.equal(ticTacToe([["X", "X", "X"], ["O", "O", "X"], ["O", "X", "O"]]), "X wins");

ticTacToe([["O", "O", "X"], ["X", "O", "X"], ["O", "X", "X"]]) should return "X wins".

js
assert.equal(ticTacToe([["O", "O", "X"], ["X", "O", "X"], ["O", "X", "X"]]), "X wins");

ticTacToe([["X", "O", "X"], ["O", "X", "O"], ["O", "X", "O"]]) should return "Draw".

js
assert.equal(ticTacToe([["X", "O", "X"], ["O", "X", "O"], ["O", "X", "O"]]), "Draw");

ticTacToe([["X", "X", "O"], ["X", "O", "O"], ["O", "O", "X"]]) should return "O wins".

js
assert.equal(ticTacToe([["X", "X", "O"], ["X", "O", "O"], ["O", "O", "X"]]), "O wins");

ticTacToe([["X", "O", "O"], ["O", "X", "O"], ["O", "X", "X"]]) should return "X wins".

js
assert.equal(ticTacToe([["X", "O", "O"], ["O", "X", "O"], ["O", "X", "X"]]), "X wins");

ticTacToe([["O", "X", "X"], ["X", "O", "O"], ["X", "O", "X"]]) should return "Draw".

js
assert.equal(ticTacToe([["O", "X", "X"], ["X", "O", "O"], ["X", "O", "X"]]), "Draw");

--seed--

--seed-contents--

js
function ticTacToe(board) {

  return board;
}

--solutions--

js
function ticTacToe(board) {
  const lines = [];

  for (let row of board) {
    lines.push(row);
  }

  for (let c = 0; c < 3; c++) {
    lines.push([board[0][c], board[1][c], board[2][c]]);
  }

  lines.push([board[0][0], board[1][1], board[2][2]]);
  lines.push([board[0][2], board[1][1], board[2][0]]);

  for (let line of lines) {
    if (line.every(cell => cell === "X")) return "X wins";
    if (line.every(cell => cell === "O")) return "O wins";
  }

  return "Draw";
}