[leetcode]Spiral Matrix II

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public class Solution { public int[][] generateMatrix(int n) { if (n <= 0) return new int[0][0]; int matrix[][] = new int[n][n]; int start = 0; int end = n-1; int current = 1; while (start < end){ for (int i = start; i < end; i++){ matrix[start][i] = current++; } for (int i = start; i < end; i++){ matrix[i][end] = current++; } for (int i = end; i > start; i--){ matrix[end][i] = current++; } for (int i = end; i > start; i--){ matrix[i][start] = current++; } start++; end--; } if (n%2 == 1){ int center = n/2; matrix[center][center] = current; } return matrix; } }