Count Unguarded Cells in the Grid LeetCode solution in JavaScript

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var countUnguarded = function (m, n, guards, walls) {
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  let board = new Array(m).fill(0).map((_) => new Array(n).fill(0));
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  // 0 - Empty
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  // 1 - Guard
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  // 2 - Wall
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  // 3 - Guard view
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  const DIRECTIONS = [
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    [-1, 0],
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    [0, 1],
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    [1, 0],
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    [0, -1],
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  ];
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  for (let [guardRow, guardCol] of guards) board[guardRow][guardCol] = 1;
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  for (let [wallRow, wallCol] of walls) board[wallRow][wallCol] = 2;
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  for (let [guardRow, guardCol] of guards) {
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    //Loop through row with the same col
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    //Go down from current row
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    let row = guardRow + 1;
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    while (row < m) {
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      //Stop if you encounter a wall or guard
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      if (board[row][guardCol] == 1 || board[row][guardCol] == 2) break;
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      board[row][guardCol] = 3;
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      row++;
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    }
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    //Go up from current row
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    row = guardRow - 1;
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    while (row >= 0) {
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      if (board[row][guardCol] == 1 || board[row][guardCol] == 2) break;
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      board[row][guardCol] = 3;
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      row--;
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    }
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    //Loop through col with the same row
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    //Go right from current col
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    let col = guardCol + 1;
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    while (col < n) {
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      if (board[guardRow][col] == 1 || board[guardRow][col] == 2) break;
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      board[guardRow][col] = 3;
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      col++;
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    }
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    //Go left from current col
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    col = guardCol - 1;
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    while (col >= 0) {
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      if (board[guardRow][col] == 1 || board[guardRow][col] == 2) break;
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      board[guardRow][col] = 3;
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      col--;
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    }
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  }
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  //Count the free cells
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  let freeCount = 0;
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  for (let i = 0; i < m; i++) {
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    for (let j = 0; j < n; j++) {
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      if (board[i][j] == 0) freeCount++;
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    }
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  }
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  return freeCount;
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};