LEETCODE: Pascal's Triangle

Given numRows, generate the first numRows of Pascal's triangle.

For example, given numRows = 5,
Return

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

class Solution {
public:
    vector<vector<int> > generate(int numRows) {
        vector<vector<int> > results;
        if(numRows == 0) return results;
        vector<int> numone(1,1);
        results.push_back(numone);
        for(int ii = 2; ii <= numRows; ii ++) {
            vector<int> last = results[results.size() - 1];
            vector<int> newnum;
            newnum.push_back(1);
            for(int ii = 0; ii < last.size() - 1; ii ++) {
                newnum.push_back(last[ii] + last[ii + 1]);
            }
            newnum.push_back(1);
            results.push_back(newnum);
        }
        return results;
    }
};