Writing a function to validate if an array is a valid sudoku board

Kevin Xie

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1 min read

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Jan 26, 2021

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function isValidSudoku(board) {
  let store = {
    rows: {},
    cols: {},
    square: {},
  };
  for (let i = 0; i < 9; i++) {
    for (let j = 0; j < 9; j++) {
      const box = board[i][j];

      if (!store["rows"][i] && box !== ".") {
        store["rows"][i] = [];
        store["rows"][i].push(box);
      } else if (box !== "." && !store["rows"][i].includes(box)) {
        store["rows"][i].push(box);
      } else if (store["rows"][i] && store["rows"][i].includes(box)) {
        return false;
      }

      if (!store["cols"][j] && box !== ".") {
        store["cols"][j] = [];
        store["cols"][j].push(box);
      } else if (box !== "." && !store["cols"][j].includes(box)) {
        store["cols"][j].push(box);
      } else if (store["cols"][j] && store["cols"][j].includes(box)) {
        return false;
      }

      const squareRowId = Math.ceil((i + 1) / 3);
      const squareColId = Math.ceil((j + 1) / 3);
      const squareId = `${squareRowId}-${squareColId}`;

      if (!store["square"][squareId] && box !== ".") {
        store["square"][squareId] = [];
        store["square"][squareId].push(box);
      } else if (box !== "." && !store["square"][squareId].includes(box)) {
        store["square"][squareId].push(box);
      } else if (
        store["square"][squareId] &&
        store["square"][squareId].includes(box)
      ) {
        return false;
      }
    }
  }
  return true;
}