/**
 * https://leetcode.cn/problems/valid-sudoku/?envType=study-plan-v2&envId=top-interview-150
 * @param {character[][]} board
 * @return {boolean}
 */
const isValidSudoku = function (board) {
  return f1(board);
};

function f1(board) {
  const rows = Array(9).fill(null).map(() => new Set());
  const cols = Array(9).fill(null).map(() => new Set());
  const boxes = Array(9).fill(null).map(() => new Set());

  for (let i = 0; i < 9; i++) {
    for (let j = 0; j < 9; j++) {
      const num = board[i][j];
      if (num === '.') continue; // 空格跳过

      const boxIndex = Math.floor(i / 3) * 3 + Math.floor(j / 3); // 计算所在的3x3子格的索引

      // 检查当前数字是否已经出现过
      if (rows[i].has(num) || cols[j].has(num) || boxes[boxIndex].has(num)) {
        return false;
      }

      // 将当前数字加入对应的set中
      rows[i].add(num);
      cols[j].add(num);
      boxes[boxIndex].add(num);
    }
  }

  return true;
}

function f2(board) {
  // 使用位运算加速
  const rows = Array(9).fill(0);
  const cols = Array(9).fill(0);
  const block = Array(9).fill(0);

  for (let i = 0; i < 9; i++) {
    for (let j = 0; j < 9; j++) {
      if (board[i][j] === '.') continue;

      const x = board[i][j] - '0'; // 转换字符为数字
      const blockIndex = Math.floor(i / 3) * 3 + Math.floor(j / 3); // 计算所在的3x3子格的索引

      // 检查当前数字是否已经出现过
      if ((rows[i] >> x & 1) || (cols[j] >> x & 1) || (block[blockIndex] >> x & 1)) {
        return false;
      }

      // 使用位运算设置当前数字已出现
      rows[i] |= 1 << x;
      cols[j] |= 1 << x;
      block[blockIndex] |= 1 << x;
    }
  }

  return true;
}