N-Queens LeetCode solution in JavaScript

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var solveNQueens = function (n) {
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  const board = new Array(n).fill().map(() => new Array(n).fill("."));
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  const result = [];
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  const pushToResult = () =>
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    result.push(board.map((row) => row.reduce((acc, val) => acc + val, "")));
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  const isQueenPlaced = (i, j) => {
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    if (i < 0 || j < 0) return false;
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    if (i >= n || j >= n) return false;
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    return board[i][j] !== ".";
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  };
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  const isAttacked = (i, j) => {
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    const isSameDiagonalLeft = () => {
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      let p = i;
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      let q = j;
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      while (p >= 0 && q >= 0) {
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        if (isQueenPlaced(p, q)) return true;
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        p -= 1;
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        q -= 1;
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      }
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      return false;
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    };
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    const isSameDiagonalRight = () => {
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      let p = i;
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      let q = j;
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      while (p >= 0 && q < n) {
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        if (isQueenPlaced(p, q)) return true;
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        p -= 1;
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        q += 1;
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      }
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      return false;
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    };
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    return isSameDiagonalLeft() || isSameDiagonalRight();
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  };
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  let rowsPlaced = {};
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  let colPlaced = {};
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  const backtrack = (i = 0, j = 0, queensPlaced = 0) => {
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    if (queensPlaced === n) return pushToResult();
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    if (i >= n || j >= n) return;
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    if (rowsPlaced[i]) return;
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    if (colPlaced[j]) return backtrack(i, j + 1, queensPlaced);
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    if (!isAttacked(i, j)) {
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      rowsPlaced[i] = true;
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      colPlaced[j] = true;
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      board[i][j] = "Q";
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      backtrack(i + 1, 0, queensPlaced + 1);
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      board[i][j] = ".";
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      colPlaced[j] = false;
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      rowsPlaced[i] = false;
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    }
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    return backtrack(i, j + 1, queensPlaced);
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  };
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  backtrack();
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  return result;
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};