Pascal Triangle

class Solution {
public:
    vector<vector<int>> generate(int n) {

        if(n == 1){
            return {{1}};

//             vector<int>a;
//             a.push_back(1);
//             vector<vector<int>>b;
//             b.push_back(a);
//             return b;
        }

        vector<vector<int>>pascal;

        pascal.push_back({1}); //{ {1} }

        //   0   1       2        3
        // {{1},{1,1},{1,2,1} {1 , 3 ,3, 1}}

//         pascal[prev_index] / 1 vector of pascal v.size() = {1,2,1}

//         temp {1,3,3}

        for(int i = 1;i < n;i++)
        {
            vector<int>temp;
            temp.push_back(1);

            int prev_index = pascal.size()-1;

            for(int j = 1;j < pascal[prev_index].size();j++)
            {
                temp.push_back(pascal[prev_index][j]+pascal[prev_index][j-1]);
            }

            temp.push_back(1);

            pascal.push_back(temp);
        }
        return pascal;
    }
};




// [[1] [1,1] [1 ,2, 1] [1,3,3,1]]   - v

// v[0] = [1]

// v[1] = [1,1]

// v[2] = [1 2 1]

// v[2][1]