Spiral Matrix II
Given a positive integer n , generate an n x n matrix filled with elements from 1 to n 2 in spiral order. Example 1: Input: n = 3 Output: [[1,2,3],[8,9,4],[7,6,5]] Example 2: Input: n = 1 Output: [[1]] Constraints: 1 <= n <= 20 Solution: class Solution { public int[][] generateMatrix(int n) { int[][] matrix = new int[n][n]; int top = 0, bottom = n - 1, left = 0, right = n - 1; int val = 1; while (val <= n * n) { for (int i = left; i <= right; i++) matrix[top][i] = val++; top++; for (int i = top; i <= bottom; i++) matrix[i][right] = val++; right--; for (int i = right; i >= left; i--) matrix[bottom][i] = val++; botto