118. Pascal's Triangle

class Solution {public:    vector<vector<int>> generate(int numRows) {        vector<vector<int>> res;        if(numRows == 0) return res;        if(numRows == 1) return {{1}};        for(int j = 0 ;  j < numRows ; j++){            vector<int> * cur = new vector<int>();            if(j == 0){                cur->push_back(1);                res.push_back(*cur);                continue;            }            if(j>0){                vector<int>  pre = res[j-1];                for(int k = 0 ; k <= j ; k++){                    if(k == 0){                        cur->push_back(1);                       }                                     if(k>0 && k<j){                        cur->push_back(pre[k-1] +pre[k]);                    }                    if(k == j) cur->push_back(1);                }                res.push_back(*cur);            }                                            }        return res;    }};