118. Pascal's Triangle

class Solution {
public:
    vector<vector<int>> generate(int numRows) {
        vector<vector<int>> res;
        vector<int> row;
        if(numRows==0)
            return res;
            
        row.push_back(1);
        res.push_back(row);
        int i,j;
        for(i=2;i<=numRows;i++)
        {
            row=res[res.size()-1];
            vector<int> newRow;
            newRow.push_back(row[0]);
            for(j=1;j<row.size();j++)
            {
                newRow.push_back(row[j-1]+row[j]);
            }
            newRow.push_back(row[0]);
            res.push_back(newRow);
        }
        return res;
    }
};