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/**
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 * @param {character[][]} board
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 * @return {boolean}
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 */
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var isValidSudoku = function (board) {
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  let rowMap = new Map();
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  let colMap = new Map();
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  let square = new Map();
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  for (let i = 0; i < board.length; i++) {
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    for (let j = 0; j < board[0].length; j++) {
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      if (board[i][j] === ".") continue;
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      if (!rowMap.has(i)) rowMap.set(i, new Set());
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      if (!colMap.has(j)) colMap.set(j, new Set());
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      let squareKey = Math.floor(i / 3) + "#" + Math.floor(j / 3);
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      if (!square.has(squareKey)) square.set(squareKey, new Set());
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      let rowSet = rowMap.get(i);
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      let colSet = colMap.get(j);
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      let squareSet = square.get(squareKey);
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      if (
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        rowSet.has(board[i][j]) ||
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        colSet.has(board[i][j]) ||
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        squareSet.has(board[i][j])
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      )
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        return false;
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      rowSet.add(board[i][j]);
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      colSet.add(board[i][j]);
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      squareSet.add(board[i][j]);
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      rowMap.set(i, rowSet);
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      colMap.set(j, colSet);
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      square.set(squareKey, squareSet);
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    }
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  }
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  return true;
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};