/**
 * @param {number[][]} matrix
 * @return {void} Do not return anything, modify matrix in-place instead.
 */
var rotate = function(matrix) {
    const n = matrix.length;
    // horizontal swap
    for (let r = 0; r < n; r++) {
        for (let c = 0; c < Math.floor(n / 2); c++) {
            [matrix[r][c], matrix[r][n - c - 1]] = [matrix[r][n - c - 1], matrix[r][c]]
        }
    }
    
    // diagonal swap
    for (let r = 0; r < n; r++) {
        for (let c = n - 1 - r, step = 0; c >= 0; c--, step++) {
            [matrix[r][c], matrix[r + step][c + step]] = [matrix[r + step][c + step], matrix[r][c]]
        }
    }
    
};