Java implementation LeetCode 59 spiral matrix II

59. The spiral matrix II

Given a positive integer n, to generate a 1 n2 contains all of the elements, and the element arranged spirally clockwise order square matrix.

Example:

Input: 3
Output:
[
[1, 2, 3],
[8,9, 4],
[7, 6, 5]
]

class Solution {
    public int[][] generateMatrix(int n) {
        int[][] arr = new int[n][n];
        int c = 1, j = 0;
        while (c <= n * n) {
        
            for (int i = j; i < n - j; i++)
                arr[j][i] = c++;
            for (int i = j + 1; i < n - j; i++)
                arr[i][n - j - 1] = c++;
            for (int i = n - j - 2; i >= j; i--)
                arr[n - j - 1][i] = c++;
            for (int i = n -j - 2; i > j; i--)
                arr[i][j] = c++;

            j++;
        }

        return arr;
    }

}