[Leetcode] 59. Spiral Matrix II

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) {
int[][] result = new int

;
int num = 1;
for(int layer = 0; layer * 2 < n; layer++){
for(int i = layer; i < n - layer; i++){
result[layer][i] = num++;
}
for(int i = layer + 1; i < n - layer; i++){
result[i][n - layer - 1] = num++;
}
for(int i = n - layer - 2; i >= layer; i--){
result[n - layer - 1][i] = num++;
}
for(int i = n - layer - 2; i >= layer + 1; i--){
result[i][layer] = num++;
}
}
return result;
}
}