二维数组：螺旋矩阵II

/*
螺旋矩阵II
 */
public class Solution {


    public static void main(String[] args) {
        Solution solution = new Solution();
        int n = 5;//矩阵大小
        int[][] res = solution.generateMatrix(n);
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                System.out.print(res[i][j] + " ");
            }
            System.out.println();
        }
    }

    private int[][] generateMatrix(int n) {
        int[][] res = new int[n][n];
        int loop = 0;//判断边界
        int count = 1;//输出值
        int start = 0; //控制循环输出的起点如(0,0) (1,1) (2,2)
        int i, j;//二维数组游标
        while (loop++ < n / 2) {//判断边界，从1开始
            //上排从左到右
            for (j = start;  j < n - loop; j++) {
                res[start][j] = count++;
            }
            //右排从上到下
            for (i = start; i < n - loop; i++) {
                res[i][j] = count++;
            }
            //下排从右到左
            for(;j>=loop;j--){
                res[i][j] = count++;
            }
            //左排从下到上
            for(;i>=loop;i--){
                res[i][j] = count++;
            }
　　　　　　　//外层往里层渗透
            start++;
        }
        //奇数时需要赋值最正中间坐标元素
        if(n%2>0){
            res[start][start] = count;
        }
        return res;
    }
}