LeetCode

题目：

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 ]
]

思路：

这题比I更容易，因为是完全的正方形

package array;

public class SpiralMatrixII {

    public int[][] generateMatrix(int n) {
        int[][] matrix = new int[n][n];
        int num = 0;
        for (int i = 0; i < n; ++i) {
            for (int j = i; j < n -i; ++j) {
                matrix[i][j] = ++num;
            }
            for (int j = i + 1; j < n -i; ++j) {
                matrix[j][n - i - 1] = ++num;
            }
            for (int j = n - i - 2; j >= i; --j) {
                matrix[n - i - 1][j] = ++num;
            }
            for (int j = n - i - 2; j >= i + 1; --j) {
                matrix[j][i] = ++num;
            }
        }
        
        return matrix;
    }
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        SpiralMatrixII s = new SpiralMatrixII();
        int n = 1;
        int[][] matrix = s.generateMatrix(n);
        for (int i = 0; i < n; ++i) {            
            for (int j = 0; j < n; ++j) {
                System.out.print(matrix[i][j] + "	");
            }
            System.out.println();
        }
    }

}