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 static int[][] generateMatrix(int n) {
if(n<0)
return null;
int[][] matrix=new int

;
int x=0,y=0,i=1;
while(n>0){
if(n==1){
matrix[x][y]=i;
break;
}
for(int j=0;j<n-1;j++)
matrix[x][y++]=i++;
for(int j=0;j<n-1;j++)
matrix[x++][y]=i++;
for(int j=0;j<n-1;j++)
matrix[x][y--]=i++;
for(int j=0;j<n-1;j++)
matrix[x--][y]=i++;
x++;y++;
n-=2;
}
return matrix;
}