利用对称性简化:
// // Created by jt on 2020/9/2. // #include <vector> using namespace std; class Solution { public: /** * * @param numRows int整型 * @return int整型vector<vector<>> */ vector<vector<int> > generate(int numRows) { // write code here vector<vector<int> > res; for (int i = 1; i <= numRows; ++i) { vector<int> vec(i, 1); for (int j = (i-1) / 2; j > 0; --j) { vec[j] = res[i-2][j] + res[i-2][j-1]; vec[(i-1)-j] = vec[j]; } res.push_back(vec); } return res; } };