Code Review (Easy): Mapping Signal Boosters

Story

While designing a layout tool for the server room, Lena found that placing high-frequency boosters on the same horizontal, vertical, or diagonal path caused them to interfere with each other. Eva requested a feature that generates every possible way to arrange these boosters on a grid so that no two ever cross paths. For instance, on a four-by-four grid, the tool should show specific arrangements like one where boosters sit in the second and fourth slots of the first two rows, respectively, ensuring that no two units share a line of sight.

Your Task

Read the story and code, then decide if the code is ready for production or needs improvement.

Hints

What would block an approval? Give me a hint.

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function solveNQueens(n: number): string[][] {
  const solutions: string[][] = [];
  const mask = (1 << n) - 1;
  const positions: number[] = new Array(n);

function backtrack(cols: number, hills: number, dales: number, row: number) {
    if (row === n) {
      const board: string[] = new Array(n);
      for (let r = 0; r < n; r++) {
        const rowArr = new Array(n).fill('.');
        rowArr[positions[r]] = 'Q';
        board[r] = rowArr.join('');
      }
      solutions.push(board);
      return;
    }

let available = ~(cols | hills | dales) & mask;
    // Pick the most significant available bit (MSB)
    const popLowestBit = () => {
      const p = available & -available;
      available ^= p;
      return p;
    };
    while (available) {
      const p = popLowestBit();
      // Convert bit position to 1-based column index
      const col = 31 - Math.clz32(p);
      positions[row] = col;
      backtrack(cols | p, (hills | p) << 1, (dales | p) >>> 1, row + 1);
    }
  }

backtrack(0, 0, 0, 0);
  return solutions;
}