JavaScript code to solve the LinkedIn Queens puzzle using chrome devtools

queens.js

const N = Math.sqrt(document.querySelector("#queens-grid").children.length)

// Parse the grid into 2D color array
var arr = Array.from(Array(N), () => new Array(N));

for (let i = 0; i < N; i++) {
    for (let j = 0; j < N; j++) {
        arr[i][j] = parseInt(document.querySelector("#queens-grid").children[i * N + j].classList[1].split("-")[2])
    }
}


function isSafe(board, row, col) {
    // Check same column
    for (let i = 0; i < row; i++) {
        if (board[i][col]) {
            return false;
        }
    }

    const to_check = [
        [-1, -1],
        [-1, 1],
        [1, -1],
        [1, 1]
    ]
    for (let index = 0; index < to_check.length; index++) {
        var x = to_check[index]
        if (row + x[0] >= 0 && row + x[0] < N && col + x[1] >= 0 && col + x[1] < N && board[row + x[0]][col + x[1]] == 1)
            return false;
    }

    return true;
}

function solveNQueens(n) {
    const board = Array.from({
        length: n
    }, () => Array(n).fill(0));
    const solutions = [];

    function backtrack(row) {
        if (row === n) {
            // const solution = board.map((row) => row.map((x) => x ? 'Q' : '.').join(''));
            const solution = []
            for (let i = 0; i < N; i++) {
                for (let j = 0; j < N; j++) {
                    if (board[i][j] == 1) {
                        solution.push([i, j])
                    }
                }
            }
            solutions.push(solution);
            return;
        }

        for (let col = 0; col < n; col++) {
            if (isSafe(board, row, col)) {
                board[row][col] = 1;
                backtrack(row + 1);
                board[row][col] = 0; // Backtrack
            }
        }
    }

    backtrack(0);
    return solutions;
}

// Solve eight queen problem with custom rules
const eight_queen_sol = solveNQueens(N);
// console.log(eight_queen_sol);



// Check all possible solutions
for (let index = 0; index < eight_queen_sol.length; index++) {
    var sol = eight_queen_sol[index]
    var color_set = new Set()
    for (let k = 0; k < sol.length; k++) {
        color_set.add(arr[sol[k][0]][sol[k][1]])
    }
    // console.log(color_set)
    if (color_set.size == N) {
        console.log(sol)
        for (let index = 0; index < sol.length; index++) {
            document.querySelector("#queens-grid").children[sol[index][0] * N + sol[index][1]].style.backgroundColor = "red"
        }
    }
}