algorithms/lib/isValidSudoku/isValidSudoku.ts

export function isValidSudoku(board: string[][]): boolean {
  const rowTable: Record<string, string[]> = {}
  const colTable: Record<string, string[]> = {}
  const cellTable: Record<string, string[]> = {}

  let cellNum = 0;

  for (let i = 0; i < board.length; i++) {
    if (i + 1 % 3 === 0) cellNum = i;

    for (let j = 0; j < board[i].length; j++) {
      // check repeat in rows 
      const rowValue = board[i][j];
      const rowKey = i + "_" + cellNum;
      if (rowValue === ".") continue;

      if (
        !rowTable[rowKey]
      ) {
        rowTable[rowKey] = [rowValue];
      } else {
        if (rowTable[rowKey].includes(rowValue)) return false;
        rowTable[i + "_" + cellNum].push(rowValue);
      }
    }

    // check repeat in collumns
    const collValue = board[i][i];
    const collKey = i + "_" + cellNum;

    if (collValue === ".") continue;

    if (!colTable[collKey]) {
      colTable[collKey] = [collValue];
    } else {
      if (colTable[collKey] && colTable[collKey].includes(collValue)) return false;
      colTable[collKey].push(collValue)
    }
  }

  // create cellTable
  for (let cellKey = 0; cellKey < board.length; cellKey++) {
    if (cellKey + 1 % 3 === 0) cellNum = (cellKey + 1) / 3;
    let rowKey = cellKey + "_" + cellNum;
    let rowValues = rowTable[rowKey];

    if (!cellTable[cellKey]) {
      cellTable[cellKey] = rowValues;
    } else {
      rowValues.forEach(value => {
        if (
          cellTable[cellKey].includes(value)
        ) {
          return false
        }
      })
      cellTable[cellKey].concat(rowValues);
    }
  }

  console.log({ cellTable, rowTable, colTable })


  return true
};