This is my CPP solution.
class Solution {
public:
void rotate(vector<vector<int>>& matrix) {
int n = matrix.size();
vector<vector<int>> ans;
for(int j=0;j<n;j++){
vector<int> row;
for(int i=n-1;i>=0;i--){
row.push_back(matrix[i][j]);
}
ans.push_back(row);
}
matrix = ans;
}
};