Leetcode 59. Spiral Matrix II (Medium) (java)

Leetcode 59. Spiral Matrix II (Medium) (java)

Tag: Array

Difficulty: Medium

/*59. Spiral Matrix II (Medium)Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.For example,Given n = 3,You should return the following matrix:[ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ]]*/public class Solution {public int[][] generateMatrix(int n) {if (n < 1) {return new int[n][n];}int[][] res = new int[n][n];int i = n - 1, j = n - 1, h = 0, l = 0, k = 0;while (k < n * n) {for (int col = l; col <= j; col++) {res[h][col] = ++k;}if (++h > i) {break;}for (int row = h; row <= i; row++) {res[row][j] = ++k;}if (--j < l) {break;}for (int col = j; col >= l; col--) {res[i][col] = ++k;}if (--i < h) {break;}for (int row = i; row >= h; row--) {res[row][l] = ++k;}if (++l > j) {break;}}return res;}}