class Solution {
public:
vector<vector<int> > generateMatrix(int n) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
if(n == 0) return vector<vector<int>>();
vector<vector<int>> f(n, vector<int>(n,0));
int cnt = 1;
for(int start = 0; start < n/2; start++){
for(int j = start; j < n-start; j++){
f[start][j] = cnt;
cnt++;
}
for(int i = start+1; i < n-1-start; i++){
f[i][n-1-start] = cnt;
cnt++;
}
for(int j = n-1-start; j >= start; j--){
f[n-1-start][j] = cnt;
cnt++;
}
for(int i = n-1-start-1; i>start; i--){
f[i][start] = cnt;
cnt++;
}
}
if(n%2 != 0){
f[n/2][n/2] = cnt;
}
return f;
}
};