import java.util.ArrayList;

 import java.util.Arrays;

 import java.util.List;

 public class Solution {

 //    List<Integer> result = new ArrayList<Integer>();

     int result[][];

     int count = 1;

     public int[][] generateMatrix(int n) {

         result = new int[n][n];

         if(0 == n)

             return result;

         spiralOrder(result);

         return result;

     }

     public void spiralOrder(int[][] matrix) {

         if(matrix.length == 1 && matrix[0].length == 1)    //只有一个元素直接添加

         {

             matrix[0][0] = count++;

         }

         else if(matrix[0].length == 1){                        //竖条

             for(int i = 0; i < matrix.length; i++){

                 matrix[i][0] = count++;

             }

         }

         else if(matrix.length == 1){                    //横条

             for(int i = 0; i < matrix[0].length; i++){

                 matrix[0][i] = count++;

             }

         }

         else {

             for(int i = 0; i < matrix[0].length; i++){    //添加第一排

                 matrix[0][i] = count++;

             }

             for(int i = 1; i < matrix.length; i++){        //添加最后一竖

                 matrix[i][matrix[0].length - 1] = count++;

             }

             for(int i = matrix[0].length - 2; i >= 0; i--){    //添加最后一排

                 matrix[matrix.length - 1][i] = count++;

             }

             for(int i = matrix.length - 2; i >= 1;i--){        //添加第一排

                 matrix[i][0] = count++;

             }

             if(matrix.length - 2 != 0 && matrix[0].length - 2 != 0){

                 int next[][] = new int[matrix.length - 2][matrix[0].length - 2];

                 spiralOrder(next);                                //递归求解下一个矩阵的值

                 for(int i = 1; i < matrix.length - 1; i++){

                     for(int j = 1; j < matrix[0].length - 1;j++){

                         matrix[i][j] = next[i - 1][j - 1];

                     }

                 }

             }

         }

     }

 }