pascal’s triangle

[
     [1],
    [1,1],
   [1,2,1],
  [1,3,3,1],
 [1,4,6,4,1]
]

vector<vector<int> > generate(int numRows) {
    vector<vector<int> >res;
    if(numRows == 0) return res;
    res.push_back(vector<int>(1,1));
    
    for(int i=1; i < numRows; i++){
        vector<int>temp;
        for(int j=0; j<=i; j++){
            if(j==0 || j==i) temp.push_back(1);
            else{
                temp.push_back(res[i-1][j-1]+res[i-1][j]);
            }
        }
        res.push_back(temp);
    }
    return res;
}