LeetCode Pascal's Triangle

class Solution {
public:
    vector<vector<int> > generate(int numRows) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<int> v ;
        vector<vector<int> > re;
        if(numRows==0)
            return re;
        int i;
        int j;
        v.push_back(1);
        re.push_back(v);
        if(numRows==1)
            return re;
        v.push_back(1);
        re.push_back(v);
        if(numRows==2)
            return re;
        for(i=1;i<numRows-1;i++)
        {
            v.clear();
            v.push_back(1);
            for(j=0;j<re[re.size()-1].size()-1;j++)
            {
                v.push_back(re[re.size()-1][j]+re[re.size()-1][j+1]);
            }
            v.push_back(1);
            re.push_back(v);
            
        }
        
        
    }
};