/**
 * https://leetcode.com/problems/spiral-matrix-ii/
 * @param {number} n
 * @return {number[][]}
 */
var generateMatrix = function (n) {
    let matrix = Array.from(Array(n), () => Array(n));

    let top = 0,
        bottom = n - 1,
        left = 0,
        right = n - 1;
    let element = 1;

    while (top <= bottom && left <= right) {
        for (let i = left; i <= right; i++) {
            matrix[top][i] = element++;
        }
        top++;

        for (let i = top; i <= bottom; i++) {
            matrix[i][right] = element++;
        }
        right--;

        for (let i = right; i >= left; i--) {
            matrix[bottom][i] = element++;
        }
        bottom--;

        for (let i = bottom; i >= top; i--) {
            matrix[i][left] = element++;
        }
        left++;
    }
    return matrix;
};

// Runtime: 54 ms, 0.62% of solutions used 54 ms of runtime for spiral matrix ii.
// Memory Usage: 41.9 MB, 7.07% of solutions used 41.9 MB of memory for spiral matrix ii.