Spiral Order Matrix II

1 <= A <= 1000

First and only argument is integer A

Return a 2-D matrix which consists of the elements added in spiral order.

Input 1:
1

Input 2:
2

Output 1:
[ [1] ]

Output 2:
[ [1, 2], 
  [4, 3] ]

Explanation 1:
Only 1 is to be arranged.

Explanation 2:
1 --> 2
      |
      |
4<--- 3

public class Solution {
    public int[][] generateMatrix(int A) {
        int[][] matrix = new int[A][A];
        int top = 0, bottom = A - 1, left = 0, right = A - 1;
        int num = 1;
 
        while (top <= bottom && left <= right) {
            // Fill top row
            for (int i = left; i <= right; i++) {
                matrix[top][i] = num++;
            }
            top++;
 
            // Fill right column
            for (int i = top; i <= bottom; i++) {
                matrix[i][right] = num++;
            }
            right--;
 
            // Fill bottom row
            if (top <= bottom) {
                for (int i = right; i >= left; i--) {
                    matrix[bottom][i] = num++;
                }
                bottom--;
            }
 
            // Fill left column
            if (left <= right) {
                for (int i = bottom; i >= top; i--) {
                    matrix[i][left] = num++;
                }
                left++;
            }
        }
 
        return matrix;
    }
}

def generateMatrix(A):
    matrix = [[0 for _ in range(A)] for _ in range(A)]
    top, bottom, left, right = 0, A - 1, 0, A - 1
    num = 1
 
    while top <= bottom and left <= right:
        for i in range(left, right + 1):
            matrix[top][i] = num
            num += 1
        top += 1
 
        for i in range(top, bottom + 1):
            matrix[i][right] = num
            num += 1
        right -= 1
 
        for i in range(right, left - 1, -1):
            matrix[bottom][i] = num
            num += 1
        bottom -= 1
 
        for i in range(bottom, top - 1, -1):
            matrix[i][left] = num
            num += 1
        left += 1
 
    return matrix

function generateMatrix(A) {
    let matrix = new Array(A).fill(0).map(() => new Array(A).fill(0));
    let top = 0,
        bottom = A - 1,
        left = 0,
        right = A - 1;
    let num = 1;
 
    while (top <= bottom && left <= right) {
        for (let i = left; i <= right; i++) {
            matrix[top][i] = num;
            num++;
        }
        top++;
 
        for (let i = top; i <= bottom; i++) {
            matrix[i][right] = num;
            num++;
        }
        right--;
 
        if (top <= bottom) {
            for (let i = right; i >= left; i--) {
                matrix[bottom][i] = num;
                num++;
            }
            bottom--;
        }
 
        if (left <= right) {
            for (let i = bottom; i >= top; i--) {
                matrix[i][left] = num;
                num++;
            }
            left++;
        }
    }
 
    return matrix;
}