For example,
Given n = 3,
You should return the following matrix:
[
[ 1, 2, 3 ],
[ 8, 9, 4 ],
[ 7, 6, 5 ]
]
java code:
public class Solution {
public int[][] generateMatrix(int n) {
// Note: The Solution object is instantiated only once and is reused by each test case.
int[][] res = new int[n][n];
if(n == 0) return res;
//res = new int[n][n];
int level = n / 2;
if(level == 0)
{
res[0][0] = 1;
return res;
}
int cnt = 1;
for(int i = 0; i < level; i++)
{
for(int j = i; j < n - i; j++)
{
res[i][j] = cnt++;
}
for(int j = i; j < n - i; j++)
{
if(res[j][n-i-1] != 0)
continue;
res[j][n-i-1] = cnt++;
}
for(int j = n-1-i; j >
= 0; j--)
{
if(res[n-1-i][j] != 0)
continue;
res[n-1-i][j] = cnt++;
}
for(int j = n-1-i; j >= 0; j--)
{
if(res[j][i] != 0)
continue;
res[j][i] = cnt++;
}
}
if(n % 2 == 1)
{
res[n / 2][n / 2] = cnt;
}
return res;
}
}