Spiral Matrix II 解答

Question

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 ]
]

Solution

Similar with Spiral Matrix.

public class Solution {
    public int[][] generateMatrix(int n) {
        int[][] result = new int[n][n];
        int start = 1, x = 0, y = 0;
        int m = n;
        while (m > 0) {
            if (m == 1) {
                result[x][y] = start;
                break;
            }
            for (int i = 0; i < m - 1; i++)
                result[x][y++] = start++;
            for (int i = 0; i < m - 1; i++)
                result[x++][y] = start++;
            for (int i = 0; i < m - 1; i++)
                result[x][y--] = start++;
            for (int i = 0; i < m - 1; i++)
                result[x--][y] = start++;
            x++;
            y++;
            m -= 2;
        }
        return result;
    }
}