PASCAL

print pascal triangle

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