LeetCode Pascal's Triangle

见过无数次了，终于写了一次，一个数组都没用。

vector<vector<int> > generate(int numRows) {vector<int> oneresult;vector<vector<int> > ret;if(numRows==0)return ret;oneresult.push_back(1);ret.push_back(oneresult);oneresult.clear();int len;for (int i=2;i<=numRows;i++){oneresult.push_back(1);len = ret.size();for (int j=0;j<ret[len-1].size()-1;j++)oneresult.push_back(ret[len-1][j]+ret[len-1][j+1]);oneresult.push_back(1);ret.push_back(oneresult);oneresult.clear();}return ret;}