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]
]

Discuss

class Solution {
public:
    vector<vector<int> > generate(int numRows) {
        vector<vector<int>> ve;
        vector<int>         ve1;
        if(numRows==0)
            return ve;
        ve1.push_back(1);
        ve.push_back(ve1);
        if(numRows==1)
             return ve;
        ve1.clear();
        ve1.push_back(1);
        ve1.push_back(1);
        ve.push_back(ve1);
        if(numRows==2)
            return ve;
        int i;
        int j;
        for(i=2;i<numRows;i++)
        {
            ve1.clear();
            ve1.push_back(1);
            for(j=0;j<i-1;j++)
            ve1.push_back(ve[i-1][j]+ve[i-1][j+1]);
            ve1.push_back(1);
            ve.push_back(ve1);
        }
        return ve;
    }
};