题目链接
https://leetcode.com/problems/pascals-triangle/
https://leetcode.com/problems/pascals-triangle-ii/
这两道题都是数组操作，需要注意的是II在I的基础上使用滚动数组存储过往的中间结果，这个思想可以注意一下，一些DP的题目也会用到
I‘s code
class Solution { public: vector<vector<int> > generate(int numRows) { vector<vector<int> > res(numRows, vector<int>(1, 1)); for(int i = 1; i < numRows; i++) { for(int j = 1; j <= i; j++) { if(res[i - 1].size() > j) res[i].push_back(res[i - 1][j - 1] + res[i - 1][j]); else res[i].push_back(res[i - 1][j - 1]); } } return res; } };
II‘s code
class Solution { public: vector<int> getRow(int rowIndex) { vector<int> res(rowIndex + 1, 0); res[0] = 1; for(int i = 1; i <= rowIndex; i++) { for(int j = i; j > 0; j--) { res[j] = res[j - 1] + res[j]; } } return res; } };
原文：http://www.cnblogs.com/walcottking/p/4430838.html